Transcript for:
Understanding Adaptive Immune Responses

hi class dr. Jim here in this lecture we're going to be looking now at the adaptive or acquired immune response or immunity that we have in the human system now one interesting thing about this is this is a form of immunity that's only found in vertebrates anything below that level in plants and in lower invertebrate animals only have kind of the innate defense mechanism which is designed to attack attack attack eat things that aren't supposed to be there we looked at that inflammation and use white blood cells to kind of get rid of the unknown specific pathogen what we're going to look at today is a completely different system and it's really called the third line of defense and what what's interesting about this this has two specific lymphocytes involved there are the B cells and the T cells and again they get their name from where they mature and maturation of these cells means where do they gain the receptor so that's going to be a big thing when we look at that today okay so that's kind of what we're going to look at is the B and T cells and where they come from the other thing you're gonna see is really interesting is that there's a lot of specificity so one thing you got to think about is that you have millions upon billions of both B and T cells each one of them are specific for a certain type of pathogen meaning that each B cell that you have or each T cell that you have and the way I like to compare it and I always use in microbiology is kind of thinking it as ice cream each one likes a specific flavor or ice cream and that's the only one that they'll go after and respond to if that flavor of ice cream is shown to them and so that's kind of how we think about it so you think about the millions and billions of different types of pathogens out there that can affect us each B and T cell responds to one specific type and so think of it that way as we go through the other big thing is that you do create memory so if you see that pathogen the first time your B and T cells will respond hopefully and then what will happen is once you have that proliferation you'll actually make these cells called memory cells which are kind of put into the repertoire you make more of and they're kind of just there to remember what you saw before so it kind of explains why you don't get sick twice if you get chickenpox you get it typically once and then you never get it again because the virus doesn't change that much over time and the next time your body sees it it recognizes it right away puts up an immune response and then gets rid of it it's another reason why we vaccinate and so vaccines basically trick the body into doing a primary response to make memory cells to it and then you have the secondary response which we're going to look at today which is your memory cells to remember what it saw so if it sees the real pathogen it now has those cells to respond right away fight off the infection and you don't get sick so that's kind of the the reason why we use vaccines and why really vaccines have increased our lifespan by quite a bit of years because of this ability not to have to see every natural pathogen in trying to build and develop response because every time we get sick there's always the possibility that we go too far or get too much of an immune response or not enough from you in response that it could potentially kill us and so that's always the issue I don't want to end on a down note but that's kind of what we look at and vaccines allow us to do these things safely to develop a memory to it so that we don't get sick and so that's a really good thing too as we look at that so that's what we're going to look at today is really the adaptive or acquired immunity taking a long time to introduce it but that's kind of what we're looking at this picture here is a very broad picture of what we're gonna look at today again the two main cells are gonna be talking about are B cells and T cells and again T cells there's two types there's the T helper cells and the T set ataxic cells and again we'll look at what the their functions are and what they do but really it's to promote a response a specific response and then gain memory so that the next time you see the same pathogen you can fight it and take it and then get rid of it so that's the idea okay so let's take a look at what we're gonna look at today so we're gonna talk about what is adaptive meaning and so we've already am kind of or I've already described a little bit about what an adaptive immunity is and again so it's lymphocytes the B and T cells we're gonna look at how does it differ the innate immunity I already mentioned that one is specificity the second one is making memory innate immunity doesn't do either one it doesn't care if it's a virus bacteria are our eukaryotic pathogen is just gonna respond to whatever is there that's not supposed to be there and then those guys never remember what they see so if you get the same bacteria it's gonna do the same thing next time there's no immediate response it's just gonna kind of do the same response as before with the third line of defense or the adaptive immunity you have specificity and you make memories so that the next time you have this overwhelming response that you don't get sick and so we'll look at that why that happens okay another thing we're gonna look at or what are the parts of the adaptive immunity and how does it work so we're going to talk about the B cells the T cells and then kind of go through and how does this whole thing respond and work and then finally we're gonna look at some disruptions to immunity and that's an important thing because you think that with all these great defenses and everything else we never get sick but there's always those issues that happen and so we're gonna look at what happens when the immune system doesn't play nice or the immune system kind of fails on us and so we get things like allergies or auto immunities or sometimes specific diseases that target our immune system and wipe them out so look at all those different things where we can have effects on immunity and why people are on certain drugs today and that stuff to look at that immune immune issue that goes on with it so let's take a look we'll go through explain what adaptive immunity is first we'll go through that and then finally look at what causes some of these disruptions to actually occur all right so again the first thing is is that the recognition response and so again adaptive immunity or acquired because you build this over your lifetime develops after an exposure to agents such as microbes toxins or other foreign substances so in order for this to act you actually have to be exposed to something you may call these cells prematurely and then they're just kind of sitting there waiting to respond and so they're kind of in this sequester state where they're kind of sleeping until they get activated and then they make a response oh look at it and again it's a very involves a very specific response to pathogens and so again these pathogens come and again we're gonna look at the adaptive work and vertebrates only were you have a moral response which is essentially your b-cells and then the site attacks are cell mediated response which are your t-cells and we'll talk about that as we go on now again the main components of this third line of defense is going to be your b-cells and your t-cells and really what where they get their name from is where they mature and again maturation just means where do they gain these receptors and so before they're called immature B and T cells and they don't have the receptors it's kind of like the rite of passage or gaining their drivers license so now they become independent and so for the B cells where they gain that driver's license is where they're made which is in the bone marrow so they are born in the bone marrow they stay in the bone marrow and gain their receptors in the bone marrow and then move on from there and they become adults or essentially activated they're not really activated but again mature B cells in this sense T cells on the other hand are made in the bone marrow but then they leave the bone marrow it's immature so they leave the house before they gain their driver's license and then they get their driver's license in this little tiny organ called the thymus and that sinus it's right in the top of your chest right here in that little organ basically and it's really more of a gland but we can call it organ today and then these T cells migrate there and then they gain their drivers license there so they get the receptor there and then they can go on and become activated after this point and so remember getting mature so when we talk about mature B and T cells means that they now have these purple receptors on them before that time they're called immature and so those cells can't respond until they get their drivers license so it's kind of moving from like I said childhood to adulthood by gaining these receptors and that's kind of the rite of passage these cells mature and the bone marrow that's why they're called B cells for bone marrow and the T cells mature in the thymus and that's why they become or called T cells okay so that's where they get their name now again for this to happen we look at how these guys respond and so again antigens are really any foreign material that causes a response and so these are what the B and T cells react to again on the BNC cells when we're talking with chirpy cells they have what is called the antigen receptor and b-cells that's called an antibody and then I T cells is called the t-cell receptor and I like this little sign and it used this quite a bit just to kind of remind you what the B cells are designed for what the T cells are for these cells that basically attack invaders that are outside the cells those are floating in the bloodstream in the extracellular spaces or other parts of the body that really are outside of cells T cells go after cells that are infected that don't look right something's wrong with them and you kill and destroy those cells that just something's not right so think of this as kind of the go-getter kind of a lot of times for bacterial fungal infections different things like that because those are typically outside of cells where the T cells are going to be more for either intracellular parasites so things that get inside and stay inside or viruses and so viruses again attack inside the cells with their DNA and RNA and so when a cell is starting to make new viral particles the T cells are gonna respond and try and kill it before it can release those viruses out into the world okay and so that's kind of the idea now like it mentioned before at the beginning each one of these receptors that are out here the B cell receptor which is antibody and the T cell receptor are are specific for one type of pathogen and so think of it as a flavor of ice cream so let's say this guy likes vanilla this B cell this T cell likes chocolate and again these will only respond to chocolate these will only respond to vanilla if they have this type and again when we talk about antigens that's any foreign molecule or protein or anything else that's deemed foreign in the body and again on that antigen you have multiple sites which the antibody or T cell could by 2 or T cell receptor could bind to and what we call that specific site is called an epitope so you can kind of see here this is a little epitope here where this antibody can recognize it antibody to recognizes this epitope antibody one this one an antibody for this one so each one is very specific and so again you can think of it as it's very simply vanilla chocolate strawberry banana or whatever and again kind of looking at those different things and you can kind of call each one a different flavor that the bodies respond to and this antibody for will only respond to if again we said this was vanilla will only respond to vanilla epitopes this one will and respond to chocolate this one only responded strawberry and this one only to banana or whatever whatever you know you can use whatever you'd like there whatever your favorite flavors are but that's kind of how it is and so if you think of it that way I think it kind of boils it down and makes it a little bit under easier to understand oh I get it chocolate okay I like chocolate that's the only in flavor if that was the only flavor ice cream you could like then that's the only one you're gonna get every time you go to the ice cream store you're gonna order chocolate because that's the only one you like and so that's gonna be how these things respond so these antibodies can only respond to a certain flavor and the same thing goes with the T cells the T cells have a specific receptor the only like one flavor of ice cream and they're only gonna respond to that flavor once it gets introduced to them and we'll talk about that here in a little while okay so again each view cell has a y-shaped molecule with a heavy and light chain and this is what an antibody looks like so think of a big Y like the YMCA so if you're going to a wedding you know they always do the YMCA and so again think of that as an antibody because that's kind of the shape of it and you have this heavy chain and this in the light chain so light chains are the small pieces on the outside and then you have the heavy chains on that inside and again they're just protein structures that look like this now they have two regions you see the V and the C the V is the variable region and this is what gives it its quality or principle of liking only a specific flavor the C is the C stands for a constant and the constant means that's where they're gonna bind to a cell we're binding to each other we're going to look at some of the different classes of antibody a little later but I just want you to think that the C is always bound to the cell or to another antibody where the V is where it's going to bind to the antigen and so that's the antigen binding site we're gonna see how this becomes the variable and why only each variable likes only a specific flavor so think of it that way this is where the flavor component comes in the rest of it is just the normal structure that you find in every receptor of antibody and again this is either gonna allow it to bind to cells or to bind to each other and we'll talk about that here see that okay so what happens so the B cell remember the mature B cells gains it regains its receptor and it's only gonna like one type of flavor here comes the antigen with that flavor so again let's say this guy likes vanilla here's the vanilla antigen or epitope and so it will bind to it once it binds to it that b-cell becomes activated it kind of sends out this little electric shock home and it basically turns on the silences okay we got our vanilla hot damn let's go make some new cells and what happens is this cell gets activated and it starts making new cells and so one of the cells that it makes are these things called plasma cells and plasma cells are essentially little factories that that essentially just produce tons and tons of antibody and so for about three weeks of life that they're alive for they just make a ton of antibody and that's all they do and they're gonna make that vanilla flavor to recognize all these different pathogens that have the vanilla receptor on it and so it doesn't discriminate there as long as it has a vanilla receptor antibodies going to bind to it and then it's going to recognize and then it's going to accept that now the other thing that's out there is a lot of times you'll have these leftover antibodies from a previous time they're just kind of free-floating antibodies stick around for a little while I'd say a couple weeks in your in your serum and maybe even up to a couple of months and then sometimes these antibodies are free-floating so the when you produce these plasma cells they don't stay attached to the B cells but they just get released out into the cytoplasm or now the cytoplasm but into the blood or extracellular fluid and so they're just kind of free-floating around and this will be used to either tag the pathogen or for other other things like neutralization of a toxin or a virus or sometimes even activating complement we'll talk about that here in a little bit but that's kind of what these things are and so again they can bind these things up grab them and then and then kind of flag them down to say eat this and get rid of it so again kind of using the second line of defense and saying eat these things while they're there so that's that's how the B cells work and again we'll talk about a little bit more about that here in a lot now for T cells same type of thing they have again in the T cell receptor now the T cell receptor was different between that and the antibody is like it said before the antibody can be secreted out and float around t-cell receptors always stay with the t-cell and again it's kind of the same thing but you don't have the Y shape you only have one variable region and then one constant region and so again these are essentially not a Y but kind of more of just kind of these two hands grasping and looking at it so again a little less than a Y type of thing but again you have the variable which likes the flavor ice cream and then the constant which is going to be used to bind to the cell and you get this alpha and beta chain and that's that's really all you need to know about the T cell receptor other than that's going to be responsible for activating the T cell works the same way so when we get the flavor that it can recognize then it will activate the cell so again in these types of things what happens is that it will find the molecule and see it now the big difference between T cells and B cells is that B cells can just bind antigen and just bind it with their Y's so their Y's are floating around in the cell and they can just by in any free antigen T cells are a little bit more snooty and the reason for that is they have to be presented to they're not gonna go oh yeah I'll just bind these three things that are floating around you need to present it to me first before I know that it's something I have to worry about so this is where that antigen presenting cell or T helper cell kind of comes in and helps present these things to the T cells in order for that to happen and so where this is coming from is what we call this major histocompatibility complex these are found on again antigen presenting cells or APCs and again this was that macrophage so if you remember my last video I said the macrophages they eat things and then they present to out to the world saying hey look what I ate they're like a little kid that shows their mom or dad hey look what I'm eating I you know type to think well they kind of do that to the t-cell and say look what I ate let's do something about this and so they carry this molecule called the MHC and they have an MHC class 2 and again this this lecture doesn't go into it but I'll just kind of mention this real quick the MHC class 2 is the presenting hands to the T cells there's also an MHC class 1 and that's a more that writing that tells the t-cell not to kill me that's the self marker that all your cells have and so that's what they're trying to match when they're trying to match tissues is to make sure you have the right MHC so that if I didn't get a liver from another person let's say my wife wanted to donate part of her liver to me they have to match that and make sure that it will cause an immune response to me if that happens then it will reject it right away because my body will recognize as a foreign tissue and say nope I don't like that and so that's why a lot of times people have to wait a long time because they don't match and they have to find the perfect match so their immune system doesn't say yeah that's not supposed to be there get it out type of thing and so again we'll talk a little bit more about that later on in the lecture but I just kind of wanted to just to show you that there's actually two different types of MHC molecules for this lecture we'll just concern ourselves with the MHC class 2 all you have to know it is MHC this is also the HLA so if we've had another class maybe a MP or something they do talk about that as the HLA or the human leukocyte antigen and so that's what gets presented to the t-cell and that and that's again a marker that we see so this presents whatever this guy ate to the t-cell and so in order for the t-cell to recognize it has to be presented first so it's against new T so again this is what happens the t-cell comes in and says oh macrophage what did you eat oh I recognize that I see that you ate vanilla I'm gonna respond to that and so it says okay I like that vanilla flavor it can't just bind to the vanilla that's just floating out here it has to be presented to first and so in order for it to present then the t-cell can get activated and then the t-cell can divide into either T helper cells or again depending on the type of cell that it is I shouldn't say just T helper cells or T so too toxic it is given a role once again to receptor because some of them will become helper cells which help activate the immune system and others will become so toxic and we'll talk more about that as we go along but essentially you get activation these cells then can proliferate and then cause a response and just like the B cells can and then and again they go after cells that are infected on the inside and so we'll look at that as well won't get too that point okay so again the adaptive immune system has four major characteristics first is the diversity of the lymphocytes and the receptors legis at each receptor legs a different flavor ice cream so think of it like that there's also soft tolerance so there's a lack of reactive reactivity to one the own molecules and so that kind of gets with that MHC class 1 but again your your immune cells are supposed to be programmed and I say supposed to be programmed so that they don't respond to your own tissues and so they're supposed to if they bind to it say well that's me don't touch kind of thing and so then they move on sometimes that doesn't happen and then we get things called Auto immunities where your immune system is actually attacking yourself and we'll talk again more about that later on in the lecture but that's one of the things that happens you also get the proliferation of B and T cells after after activation so again that causes the immune response and then also you get memory and so one of the things I didn't mention with the plasma cells and the T cells is you also make a subset that are called memory cells that basically are now ready to respond to the next time that vanilla flavor comes into the body and so it's already there and so that's one of the big things that you'll see and we'll talk again about that when we get into specific activation so that's going to be important so again the first thing is the generation of the BN T cell diversity and again you can read through this if you'd like but they're really the thing to note is that you have these v genes and the v genes again for the differentiated D cell are up to about 40 different V combinations okay so you have 40 different D combinations that can be put together along with these J's and so that kind of gives you these different functional genes the C is always constant and never changes and remember the C is what either binds to the cell or binds to another antibody and we'll talk about that a lot so you can get any one of these for T V combinations along with one of these J combinations to make a gene so let's say here you you go ahead and you make the V 39 and the J 5 so those are going to be the two that it selects you put this together and so now the functional genes going to be v 39 eight five and that's gonna be the receptor on the cell so they're only gonna recognize let's say this is the receptor for strawberry ice cream this V 39 J v where v 38 G 2 let's say would be for vanilla and d 37 J 1 would be for chocolate or you know and and you can look it like that so you can just imagine with 40 different genes along with another 5 J's so 40 of these and 5 J's and the different combinations you can make lots and lots of different mixtures of receptors in that and again that's typically what happens in these situations and so again you make that functional gene that gets transcription where it makes this puts it together and now you make them variable in the consonant region that the constant region again is gonna stay the same from cell to cell because that never changes so it allows it to bind to the cell or other antibodies and then the V is going to only be the part that's different which again could be any combination and so you can see there's a combination of 200 different ways and again with the heavy chain there's even more combinations and so this is just showing you the light chain but for the heavy chain there's even more and so you'll see that all these different combinations leads to a millions upon millions of different D cells that recognize each specific flavor of ice cream that's out there or pathogen or antigen or epitope that you want to think of in those situations okay so again the antigen receptors are generated by random rearrangement you get then in the bone marrow or thymus they're presented and tested for self reactivity so the way that they do this is that all these B cells are lined up and so again remember B cells get the receptor in the B cell T cells gated in the thymus so let's just say in the B cell which we're in the bone marrow it basically gets presented to you before it goes out in the world so it looks at its receptor and says does that recognize self and so what it will do is take a molecule itself and kind of plug it in so it's kind of just testing you know think of it like a quality-control on an assembly line there's always someone that's always making sure nothing falls apart like let's say you're making refrigerators and you don't want the door to fall off I just think of that because of the commercial and that stuff and so what this quality control person is doing making sure that doesn't the door doesn't fall well in your bone marrow you have cells that basically are plugging in self antigens and de jure scepters to make sure that they're not defective and so if it is reactive then the cell will say nope we can't have you because we don't want to have an immune response and so will cause you to going to sell that and we'll just throw that one out that one gets the reject if it doesn't react to the self antigen then that's okay it goes on to survival now I can go sit and become four immune response when we have the cell death that's called self tolerance meaning that it can recognize self and get rid of it before it gets out into the into the environment it's out of the bone marrow now can do its job and so that's the hope that all your b-cells and t-cells are looked at first and checked sometimes we have issues with that and so sometimes these guys sneak through or there's poor quality control on the end of testing these self antigens or something else happens in the bone marrow or the T or in the thymus and so now you lose that self recognition and now that's where autoimmunity is concerned that's one way there's other ways that on immunities can happen but for for now just think of it that way that it's a quality control issue that these receptors are let out before you have a chance and so that's that's one of the issues and so that that's one problem that can happen in those situations now again what happens to these B cells and T cells once they gain their little receptors and become mature they then migrate through the lengths that system so they go through that lintz's remember that's the drainage tubes and then they park themselves in these lymph nodes and that's going to be their jobs for the rest of the life and so what happens is you get these B cells on the outside of the lymph node and then the T cells on the inside and essentially they're just there with the receptors out and that for the think of the B cells the receptors out just saying what's kind of coming my way is vanilla are gonna come my way or and the other B cells talking to the other guys I hope Charlotte comes my way so I can activate and they basically just sit there they sit and wait until they get activated and so that's what they're waiting for and waiting for them waiting for and then once that flavor comes in WAM these cells can get activated and once they get activated they start to swell up and then these lymph nodes become swollen and so whenever you get sick a lot of times you'll feel the swelling of your lymph nodes or you get a shot in the arm sometimes you'll feel it in your in your armpit and that's because that vaccine is drained into your lymph nodes and now your lymph nodes are responding you're being teased or it cells are responding and what you're feeling is that reaction the b-cell and t-cell gaining the repertoire insane whoo this is the flavor I like in that flavor then that cell with the flavors are now expanding making plasma cells to make antibodies the t-cells are responding and that and now what you're also doing is making a subset of cells that are for memory and that's gonna be the big thing there and so again these guys sit there now for the T cells those T cells sit there and they have again remember they have to be presented to so a lot of times you also will see white blood cells and T helper cells that are there ready to present to those T cells and that's going to be a big thing as well so you can kind of see the different types of activation now you also have T and B cells are in migration as well and so again they may be coming in to set up residents or they may be just kind of floating around as surveyors looking for anything that's foreign and so that's another thing that you see and then once they become activated those cells can then be released throughout the body and then they may once you make memory cells those memory cells can then go out and then go get stationed into other lymph nodes so that the next time they can respond to the same exact pathogen and just speeds up the system now the one thing to remember is that it takes time for this response to actually take place and the reason for that is because remember each one of these cells recognizes a different flavor and if that flavor does not cross that lymph node and that T cell or B cell doesn't get activated you don't respond to it and so that's the issue it takes time for this to happen so the pathogen has to work its way to the lymph node where that B or T cell might be and if it's not there it's not going to recognize it and so that's one of the issues and so everything has to be coordinated and it takes time for this to happen a lot of times when we get sick our BM T cells haven't responded yet to the thing or it's just getting to that response and now you start to feel better so it takes time for that to happen and that's one of the one of the problems with the adaptive response is a delayed reaction is that you actually have to get sick first in order for this to happen one thing we can do is take vaccines and it basically promotes further this response to fine so that vaccine will promote these B and T cells in here's to activate make memory cells and then they scattered throughout the body so that the next time you see the real pathogen they're ready to respond right away that now in every one of your lymph nodes you may have a B M T cell that respond just to chocolate and now they can respond right away make that response a bit much faster and then you don't get sick from the real pathogen and so that's kind of what the vaccine does but we'll again talk a little bit more about that in a few minutes again once they're activated so this is kind of cool this is kind of telling you what happens you have this wonderful stem cell that makes this B cell population with all these different flavors on there and again some of them get tested they all get tested so quality control if any of these recognized self they're eliminated and so you take those right out of the population before they make it or emigrate to any lymph node out in the body these cells that are not self reacted then go off to the lymph nodes they sit there and they wait for their flavor of ice cream to come so here you got this guy right here once he gets his flavor let's say it's vanilla he loves vanilla he responds to it now you get clonal selection you form these cells one one group of cells go off and they make plasma cells and again in their lifetime for about three weeks they're just going to be producing and pumping out as much antibody as possible the same antibody that recognizes the vanilla the other thing that you make is again more memory B cells and those memory b-cells will then be used to be migrating to other lymph nodes so they'll emigrate to other lymph nodes so that the next time you come in contact with vanilla boom your B cells can respond right away these cells make antibodies they go off by independent pathogens and help eliminate it and so that's the big thing not only do you get specificity so you can recognize pathogens but you make this memory that can go off and then member of this infection for a long period of time and again gives rise to effector cells into the same manage and encountered again so that's why you don't get sick a second time from the same pathogen now you may ask well why do I get a cold every year or why do you have to get a flu shot every year well those things change those viruses are really smart even though they're just infectious particles they're not even really cells they mutate over time or they have different receptors on them that are different so one year they may have chocolate the next year they have vanilla the next year they have a chocolate vanilla swirl and so again you have to get vaccinated so that your body can make that memory or you get sick from it and then you make that memory to the chocolate the vanilla the chocolate vanilla swirl but again you have to make you have to have these cells respond in order to have protection in these situations so a lot of times these are delayed and so that's why you get sick before you get response and again this is just showing you the different variety flavors this guy was vanilla chocolate strawberry boom this guy sees vanilla all right make some antibody these guys are going to just pump out antibody into this into the blood and into the extracellular spaces these guys are gonna make memory cells and go line up in different different lymph nodes or free-floating so that the next time you come across vanilla pathogen boom I can affect it and attack it and eat it the next time and do those different things okay and so the key is this amia logical memory and this is really why the vaccine works alone this is what we're doing when we vaccinate so if you go get your flu shot what happens is that again you get injected with this antigen okay so this is in the example of getting sick so let's say you didn't get the flu shot this year and then your neighbor coughs and sneezes on you and what happens is that you have this response so for the first seven days after you expose this antigen you start to get sick and then again like I said it's a delayed response because that antigen has to work to the lymph nodes that be an T cell recognizes the vanilla that's found in that flu virus and then what you get is this response so you make antibodies to that antigen and again you make this response and that response eliminates the infection and then about three weeks later you start to feel better well you start to feel here really at Dave 10 and that stuff but it may take a couple weeks to get back to complete wonderful health and then let's say you then sit next to somebody else they now have the flu they came to school that day and all of a sudden they sneeze on you and you're like ah great thanks I just got sick already I felt better and now you're sneezing on me well now because you have those memory cells those responses just take off those memory cells recognize the vanilla right away and say oh we saw that flu just a couple weeks ago boom we hit we make all these antibodies this is called the amniotic response and so what happens you make this huge response right away and the good thing about it is you don't get sick and so because you make this response right away there's no delay no sickness now what can happen and why sometimes people get a second round of flu is the the flu changes from vanilla - chocolate and so now you get re exposed but now this time it's not the vanilla flu that you got you now got the chocolate flu and then now you have to go through and you suffer through again and even though you had the vanilla response you now get sick with the chocolate and so now your body makes that and so a lot of times when they give you a vaccine they're not just giving you a vaccine for one antigen but it's for multiple antigens so that you can respond to a lot of different things and that really plays a role in how well a vaccine is gonna work especially when we talk about the flu vaccine some years it's really effective and 80 to 90 percent coverage and meaning if you got the vaccine you're not going to get sick last year it wasn't particularly good only about 20% we're actually getting protected by it and so that meant that the the antigens that they picked in there for your immune response wasn't very good and so they may have to guess six months prior to what they think the what they think the flu is going to be so they make the guess and say we think it's going to be vanilla chocolate and strawberry well what it turned out to be is raspberry banana and topia or tapioca and so they were completely wrong and so the vaccine doesn't work very well I will say though even if that is the case a lot of times though with that immune response that sometimes you can get partial activation so sometimes people that get the vaccine actually even though they density get the right antigen still have a little bit of sponsor or speed-up in response and so they do better than without and so a lot of times even if you've been vaccinated and you still get sick with the flu you actually do better and you don't have a severe disease or duration of the disease and that and so that's really one of the reasons why you really should always get your flu vaccine because again it's gonna protect you even in the cases that you still get sick is still gonna protect you in some in some aspects and you may have a less severe case of flu and then which means that you're not gonna go to the hospital there's not a chance of you developing pneumonia and potentially getting really sick and maybe dying from the disease so for my aspect being a biologist microbiologist I see it's a no brainer to go get your flu vaccine I've already got nine this year so go get yours so that you're protected and then it will only help you in the long run and that stuff you may get some exposure and some pain in your arm and that but it's better than getting sick from these things okay and so again that's what is now I've mentioned vaccines and what does vaccines do well essentially put you into this primary response and so you get exposed you get the shot in the arm and then it drains the lymph node you get the B and T cells so let's say you got the vanilla and it's that vanilla response and so there you go and then let's say now you get exposed to the vanilla flu well that flu comes on there someone sneezes and then you make this quick response and then you don't get sick and so that's really why we get vaccines and so again it allows us to span this thing and not get sick and this is what a lot of our vaccines do it protects us from mumps and measles and rubella and a lot of other things that are out there you know your tetanus shot a lot of these different things allow you to have the avoid the primer response which means getting sick and now you go right into the secondary and so long winded exhalation this is again you're avoiding with a vaccine you're avoiding the primary response because you're doing it artificially with the vaccine doing this and your body does this without too much discomfort and then when you get exposed to the real pathogen you're ready to go now again if let's say you did the flu vaccine and now you're ready to go but now you get to chocolate you may have a response but it may be muted because of the vaccine response that you have so again just talking about that and when those things can happen so that's kind of the idea between memory and getting a vaccine and all those other things I think it's really important to kind of understand that and why we vaccinate so when people say I'm not gonna vaccinate because I think I'm gonna get sick from it you can these at least tell them why do you want to put yourself from in harm's way when your body does it and now you're protected from it and that's what really you're supposed to do and that's why we vaccinate okay so hopefully got something out of that all right so what are the B and T cells do so again like I said the B cells are the guys that are outside the cells they stay typically in the blood and the extracellular fluid where the T cells are gonna attack cells that are infected so again B cells go after bacteria and eukaryotes and fungi where the T cells are gonna go after viruses and intracellular parasites so if they go inside the cell the T cells will respond if it's outside the cell the B cells gonna respond in those situations now one of the key players in all of this is the T helper cell and the T helper cell kind of helps the immune system along so what the T helper cell can do is not only activate other T cells but it can also activate B cells so that's kind of why they're a helper because they help activate the system and so that's what happens here now you can see this is the MHC and again the T helper is designated by the cd4 it has a cd4 receptor that binds to the MHC and it helps B basically helps present it it's kind of like saying here I've got something what it does is kind of reach out and help hold the receptor so that it has a really good picture of what it sees once this gets presented the T helper cell gets activated and then you get these different responses and again we'll talk more about this but again this is what happens is the T cell responds to it it sees the antigen but remember T cells have to be presented to first and that's going to be the key that's the difference between T cells and B cells in this situation now once the T cells are activated you produce these cytokines the cytokines developed the immunity and then what you do is then you make again these cells can get activated from the T cells along with these cytotoxic T cells which are the cd8 and so that's really what the helper cells do they help activate like I said they'll help turn on B cells and they'll help turn on other T cells that will and destroy and so this is why t-helper cells are so important because they help activate your system okay now again the humoral response is when again you get the activation from the T cell to the B cells now the B cells will make plasma salts which produce antibodies so the humoral means you're making the B cell response whereas with the you're also making the memory cells there but really where the Moral comes from is producing antibodies that get into the blood that are secreted out by the plasma cells and so anytime you see more immunity that's meaning B cells in producing antibody T cells go in and do that other thing and again destroy T cells and we'll talk about this a minute so what do i anybodies do and so I've mentioned a couple things that antibodies do so once they get released by the plasma cells they do a couple of different things the first thing they do is this thing where they flag pathogens and they'll bind to the specific receptor on the on the pathogen again for their epitope and what that does is it Flags phagocytes like neutrophils and monocytes to go in and eat that thing because when they see it coated with antibodies say oh I got to eat that that's something I got to eat it's not supposed to be there and it says eat me first and so that's one of the things that it does and that's a big funny word called opsonization so that just means flagging pathogens to be eaten or opsonization that's what's going on here another thing antibodies can do is essentially bind to either a virus that's free-floating out there to eliminate the virus that's floating around inside the body or a lot of times is used for toxins so you've heard of antivenoms and antitoxins that's essentially what that that's what you're taking so if you get bit by a rattlesnake a lot of times you get this venom that's circulating in your body and it causes you to maybe have paralysis well what you can do is give someone an anti-venom and it's called anti because it's an antibody that will block the venom and what it does is it basically blocks the receptor sites on the toxin so it can't bind and can't cause paralysis and we see this with a lot of different things so again one of the big things that you get with tetanus is you get that tetanus toxin which can cause flaccid paralysis so you take an antibody if you've been exposed to tetanus and that will block the toxin so that you don't get the so it can't bind to the deceit of colon receptors actually the inhibition receptors a it's not the cetyl colon receptors but the inhibition receptors in the synapse and so it prevents from getting this flaccid paralysis another things like I said the anti toxins are antivenoms which will do is block the venom so that it won't cause those things and again that's why you gotta get to a hospital if you get bit by a snake that is venomous that again you don't want it circulating through your body and causing damage you get the anti-venom and so that will help protect it another thing that it can do is it can also cause things to aggravate and so that's another thing that antibodies do is called essentially aggregation in the sense that it basically process cells are other things to a great up and form these big balls of stuff and so essentially it just basically clogs the system up and so it's good for again complement to get activated to eat these particles up but sometimes it can cause problems too and that's one of the reasons what happens when you get the wrong blood type and we're gonna go in that today but that's one of the things that antibodies can do is basically gluten ate the cells and cause them to clog up and so you can get problems of that and constant you destroyed by complement and so that's another thing as well as agglutination it's called okay so again the antigen-antibody complex made by and complement protein like it said and then that causes the cells to basically form into the pathogen leading to cell lysis and so this is a complement cascade we talked a little bit about that the series of proteins that caused that to happen and again antigen antibody responses to complement can trigger the complement for doing that and again you develop this making pores into cells and doing that as well so that's another thing that antibodies can do now as i mentioned before there's a couple of different classes of antibody and we'll just briefly talk about those real quick and where you see it and again all these guys have constant regions and so you either see them bound to other antibodies and so like the IgE and the IgM are bound to pentamer or bound to themselves and then you have some of these other guys that are bound to cells or free-floating and so that's kind of what we'll look here and so again there's five classes of antibody they're called immunoglobulins so they're basically immune proteins that are floating around in your cells called antibodies and again they have different functions the first one is IgA and it's a dimer that is bound together and typically these are called secretory antibodies because they're found in secretions and we find these in mucus saliva tears and breast milk and this is going to be important because these are antibodies mom can pass on to her baby so that baby will get some protection during the first couple months of their lives and so one of the important reasons for breastfeeding is not only providing nutrition to the child but also providing some immune surveillance to the baby while their immune system is developing and so that's one of the things that the IgA is good for is for secretory antibody the second one is the IG D which again is typically part of the b-cell receptor this is what we find in cells so the constant region is again part of the b-cell receptor that's the IG d IgE is against parasitic worms and then it's also responsible for allergic reactions and we're going to talk a little bit more about this winds look into allergies here in a few moments but Ige's are on mast cells and then those trigger these granules ations so you get the release of histamine in that and so a lot of times people look at IgE is really the bad antibody because it causes the allergic reactions in that but they're also important especially for the parasitic worms and responding to that IgG is probably the most common antibody we have this is the secreted antibody in your bloodstream and again is part of that primary secondary response that we think of an IgM is actually the first antibody that's made by the plasma cells and so your plasma cells will first make this I Jam this pentamer which will go and bind and then it will switch over to the IgG a little bit later and so I'm not sure if there's an exact reason why it goes from one to the other but maybe this is to get the early warning bell and get things clogged up so then you know you make this to kind of cause a reaction to the system because you're gonna have multiple binding with this and then once the kind of the situation is kind of stabilized then you start secreting the IgG which now is a little bit again necessary for kind of cleaning up and making sure getting rid of everything else and so this is kind of the early warning i GM first and then IG G is the second one that gets secreted and that's about if you look at it this is like the first three days after B cells get activated and make plasma cells and this is really after three days and then you get this long response of IgG after that and again I'm not really I'm not the exactly sure again an immunologist would be able to tell you right away what's the trigger mechanism in that stuff but I I like I said I think it's more about binding and how many sites this combined versus this and so this is kind of early warning early detection this is going to be secondary to kind of clean up the infection after after the process has already begun and going in full force in these situations okay now like I said the cytotoxic T cells that was you had two helper cells those were the cd4 these guys have the cd8 and so again they can either be turned on by the APC so again macrophages that have it or dendritic cells that have the MHC class to present it to and say you need to react because cells are being infected and so what these guys do once they're activated is they produce granzymes which kill and destroy infected cells so they're looking for infected cells and when those infected cells are reported these T cells go in and destroyed and so again they basically destroy the infected cell from the outside in and so you release these porphyrin molecules which create pores they also do other things like activate caspases and other things for these cells to eventually go through apoptosis and die so again they attack cells that have been infected internally so that those cells can't get the viruses all made in time so they die before the viruses can get out or you know you can think of maybe leaving cancer cells or intracellular parasites which are hiding on the inside and again they've been tipped off they respond and then they destroy those cells that are carrying those intracellular parasites that thought they were safe from the immune system but then the t-cell gets revenge and destroys that cell okay so that's going on there so just a quick review of what happens and so again you get exposure that exposure has a flavor or couple flavors to it you have the antigen-presenting cell which can presentiments directly to the T cell or can present to the T helper cell or that antigen can respond to the B cell itself and so remember B cells can just bind to it automatically if it's floating around and it recognizes it right away but the T cell remember they're snooty and they have to be presented to first either by this guy to the T helper or to this guy over here and you can see the positives that just means these can actively or positively turn on the system and so again T helper cells can activate these cells they can also activate C titles and send toxic cells and then the key is making the memory and so you make the efficient cell like the plasma cell and you make memory to it as well as again with the T cell you makes sense types of memory cells so they'll recognize the flavor as well as the active site of toxic T in case those cells are infected on the inside and then they can go after that and so again fed against intracellular pathogens in cancer these go after the extracellular pathogens and so again you kind of have two different systems but they work corden coordinated together so that they help fight whatever pathogen you have very specifically and so that kind of just gives you an idea and the key is the memory so that you have these cells again so that the next exposure you have you're ready to go you're ready to fight this thing and you don't get sick and that's gonna be the key to any system with the adaptive okay since we've talked about immunology and looked at the acquired and how this happens we need to talk about immunity and so again over time your immune system you get exposed to things and you then create immunity you make memory and so you have two types of immunity you have active immunity and you have passive immunity so I want you to think about this active immunity means you make memory and so when you make memory that means you're gonna have a collection of B and T cells that will remember that the next time you see it and so there's really two types there's called natural active immunity which is when you get sick and so the example would be you get sick from the infection you make memory cells to it so that the next time you see it you don't get sick from it and then the artificial would be a vaccination so you get injected with something that's in the lab and then your body makes memory to it that the next time you see the natural pathogen you're now protected and you don't get sick and so that's the key you make memory with active immunity whether it be from the natural pathogen or artificially and so that's going to be the key there now passive immunity means you don't make memory but you're protected for a short while and so there's two types again the natural would be getting antibodies from somewhere naturally and so most likely gonna be maternal antibodies from breastfeeding and so you may get it from there you may get some other ones that are naturally made maybe in some secretions and that stuff but typically what we think of when we think of natural passive is going to be from maternal antibodies from breast milk the other passive way is that again you get it artificially either monoclonal antibodies that are made in the lab that are in respond and we'll talk about that here in a minute or you get an antitoxin or anti-venom that's injected to you again to protect you from the venom or the toxin that may be you now have in your body and so that would be artificial and again neither one of these trigger any memory cells so you don't get activation of B or T cells but what it does is provides temporary protection so that you can survive and that again you don't get you don't get sick from from those things and again or protect you for so you don't get damaged from that and so that's passive because you don't make memory active you make memory passive you don't and again the two types natural versus artificial okay so again we can make antibodies as tools and again we can use this to fight certain things so one of the things that are out there now is called monoclonal antibodies and what this is is eventually essentially making antibodies in the lab that will go after specific infections and so in this case this is just kind of quickly showing you what happens and so what you do is you give a little mouse or a rabbit and antigen they produce antibodies so you get these antibody plasma cells you pull it out of their blood after they've been exposed to the antigen and then what you do is you do a fusion with a cancer cell and this becomes a hybridoma because it's a hybrid of the antigen in producing style and of this tumor cell now the interesting thing about tumor cells is that they go through cell reproduction without any truck since so again their cancer cells that we have in the lab that we've taken from cancer patients and then we fuse them together and so essentially you fuse by incorporating the nucleus in one so that they continue to grow without checkpoints and so what you can do is make these cells just produce antibodies because like I said these cells only last for about three weeks and then they die these cells are immortal and so they can make antibody for a long long period of time and again they make one specific type of antibody so that's why they're called monoclonal meaning they make one variety so again let's say Y we're talking about a chocolate-flavored cancer or virus you could say okay I want to make antibodies to it I make a ton of antibodies and so on all these antibodies here are going to be just for the chocolate flavor or vanilla flavor so why is this important well we can make antibodies to specific cancer cells and so if we know receptors on cancers and cancer cells that would trigger an immune response and like it said antibodies can trigger immune responses in that and then in being eaten up by phagocytes we can do that and so again if we know that a certain cancer cell in your body has a receptor on it we can make these monoclonal antibodies give them to people and then have the ramune system attack it so instead of giving them really dangerous chemotherapy drugs which kind of kill the cells kill any actively dividing cells including your immune cells and your blood cells you now actually are using your immune cells to help and get rid of this and this is what your body normally does if your T cells recognize the cancer cell and say that doesn't look right we need to do something about it then your T cells are going to respond and again it's about activating those T cells to respond and do those things and you kill those cells and so if you can do that you can actually get your T cells to do that for you and this is where medicine is going this is why it's becoming personalized because your cancer cells may have specific receptors that they're going after and again the key is you want to find a receptor that's different than self because you don't want antibodies in your body going after self cells and so that's gonna be the key so it's got to be a cancer specific receptor not one that's just found on yourselves because that means now you're putting an antibody that could hit any cell and destroy it so it's got to be specific to the cancer cell itself and so that's that's like I said that's kind of where medicines going so we can give people antibodies and trigger the immune system rather than giving them these nasty chemicals that are basically killing cells just to get rid of the cancer cell itself and so that's one of the big things that's coming along down the line okay now another thing you hear about with the again the immune system is the chance for immune rejection there's really two types and again I've talked about this before these are called MHC class ones and we have these on all our cells except blood cells think about what cells are the easiest things that we can give to anybody and that's blood and blood has a couple of different types but for this situation we're thinking about this specific again the MHC in this case and this is the MHC class 1 not the two that presents the T cells but this tells your body what is U and so you have to match this in order to get a recipient so let's say you got transplanted with either new piece of colon a liver or heart or a long it's gotta match otherwise the immune system is gonna see that and it's gonna attack and so that's where I'm sorry that's over here so your immune system will recognize it say I know transplanted organs gonna stay here because that's for and so you gotta match it up as best you can and so that's one of the problems why you just can't take anyone's heart and put it into your body because they got a match otherwise your immune system say that's not supposed to be there that's the vanilla flavor that I was programmed to take out and that t-cell will take it out and that's rejection and so a lot of times people when they get it transplant even though they get matching MHC and put on medicines for the rest of their lives so that they suppress the immune system so now they're gonna be more likely to get infections they're gonna be more likely to get sick from things because their immune system is suppressed so it doesn't attack the tissues now one that isn't really talked about a lot is this thing called graft-versus-host disease and this is when let's say you have normal tissues but now you're gonna either get a bone-marrow transplant because your bone marrow cells are bad that you may have a cancer like leukemia or something you gotta eliminate the B cells that have cancer or let's say you get in transplanted with a differ organ you know from a recipient and they have some immune cells left over well those immune cells now recognize you as foreign and they could go in and start attacking different parts of the body so let's say you got some liver from someone else well there were some VNT cells left over from the original patient you got their recipient and now goes and starts attacking your colon your heart your other parts of your body and that's called graft-versus-host so now the graft itself is actually attacking the host and this one doesn't get mentioned nearly as much as you hear about rejection of the organ but it is a possibility and so that's another reason why you want to suppress the immune system I mean when they get that transplanted organs they try and flush it out as best you can but again there's always a potential of having these cells or t-cells this is the other issue with bone marrow transplants and sometimes they don't take and the bone marrow cells that you get from the recipient are now that patient so let's say you know me and my brother who would be a match let's say I needed bone marrow first what they do is irradiated cell so they irradiated my bone marrow so I can't produce any more white blood cells that are my own and then I get a transplant from my brother well then now all my white blood cells on my T cells and B cells are now my brothers if my his cell receptor says I don't recognize your tissue and now it says it's floor and it could potentially attack me and so that's why you gotta match that as well and so that's why it's hard to do a bone marrow transplant from one person because you don't want to have that risk of having the immune cells actually attack host tissues and so that's the opposite effect that can happen and so a lot of times you hear about this most the time you don't hear about this but this is also a possibility that could happen we're the new immune cells now attack the recipients other organs in those situations and again that's called graft versus host disease again adaptive immunity protects them against many pathogens but it's not a fail-safe and again there's a lot of situations that can happen and we call this immune dysfunction and again it could be where you have excess immune response where you get autoimmunity cardiovascular issues neuro degeneration like MS or some other ones that attack the nervous system or you get access where you get again non-self either allergies hypersensitivities and that atopy and then again deficiency in your immune response could lead to cancer because you lack surveillance or infection more now you don't have part of your immune system so now you're more likely to get a secondary type of infection and again that can happen as well so first thing we're going to look at is allergies and again allergies are basically an over heightened response to something that's foreign in your body and again it doesn't happen overnight it's one of these things that develops over time and so essentially what happens is that you breathe in these allergens or you get it into your digestive system or you get it on your skin and your immune cells recognize it as foreign and that's okay but what happens is you have these special b-cells like I mentioned before that produce these IgE s and these Ige's get produced by these b-cells and typically those are cells that are found in the mucus layer so again your nose your digestive tract and that that's kind of where most of your allergies are stem from and what happens is these iges get made and they're constant region has an infinity to bind to these mast cells and mast cells are these basal fills and if you remember I talked about that these are granule cells that release granules to trigger an immune response and they're important for certain things but they're really low in number but when you get this IgE made now for this allergen you've essentially set up this ticking time bomb so what happens is you get these ideas on these mast cells they go into the into the periphery they go all throughout the body and then let's say you breathe in a new allergen the second time now these cells that have these IDs will respond they cause for the histamine to be released and that causes that allergic response and depending on how many cells you have and how quick the responses can determine whether or not you have just a little response where you may get hives or you may get at the watery eyes or stuffy nose or something else or you may get a really overwhelming response going into anaphylactic shock and that can be a bad thing as well and we're gonna look at that here in just a second so one of the things you'll do is if you know you have allergies is you may take an antihistamine like benadryl and what that does is it blocks receptors that prohibit histamine from binding to the receptors on those cells now one of the problems is is that hysteria histamines also affect the receptors in the neural pathways and so you actually get a sequester and sequester of the neural cells which actually kind of put to sleep so they don't respond as fast and that's why you kind of get sleepy when you take an antihistamine because not only does it affect the the histamine receptors on cells but it also affects the neurons and you don't get a quick response and it kind of blocks the acetylcholine receptors and that stuff so you kind of get sleepy and tired and so that's one of the things and you just kind of feel like I'm out of it I'm kind of feeling this out-of-body response and so that's one of the bad things about histamine some of the newer and allergy medications don't have as much antihistamine in it so they do other other types of responses again that are released so it's not just histamine but there's a number of other chemicals that get released as well that can be blocked as well now like I said it could be lead to anaphylactic shock which is a major problem and this is when you get this very overwhelming response and so you get very high swelling these can be things from the venom penicillin peanuts and shellfish and again with these hypersensitivity you want to carry epinephrine and what that's going to do is because one of the main problems is when histamine is released it causes vasodilation of the smooth muscle in a lot of times either in your digestive tract or in the in the blood vessels and so you get vasodilation the other thing you get is these a constriction in the respiratory system so you get very flushed so again that's where the Heights come from like this you can see here the bad hives and that student phaser dilation of the blood as well as some other atopic and nature from again histamine and that on the epithelial cells but you also get the Vizsla constriction in the bronchial tubes and so it closes that down and if you can't breathe you're in real big trouble and then that can have effect on your heart and so obviously people want to carry around if they have severe allergies is an EpiPen which they can inject in right away what it'll do is give you a shot and after Efrain and we talked about that before what epinephrine does not only does it cause bezel dilation but it also increases the heart rate so that the heart can beat faster to get blood to areas that are necessary and so again it speeds up the heart so you don't get the heart failure that could be associated with an allergic response okay so that's that's what's going on in those situations there so again severe allergies may require the epinephrine now another bad thing that can happen is the autoimmune diseases there are several out there including lupus with Roma and matatus with rheumatoid arthritis type 1 diabetes multiple sclerosis so again you can have your immune cells attacking person in the body another one that's not on here is Crohn's disease we know mewn cells attack attack the intestines in that and again there's lots of possibilities one obviously being the loss of tolerance so cell tolerance so your body doesn't recognize self anymore another big thing that they think is a lot of times is molecular mimicry that you get pathogens that are very similar to self and they do that so that again they don't get recognized by the immune system but what that could do is if they do get recognized by an immune system now they recognize self and that could happen and some of it is thought to believe or is thought to being that we live to clean of a lifestyle maybe this is the problem with vaccines and other things is that we our immune systems get bored when we're we're too clean and we're washing our hands and and you know not touching anything and using disinfectants and antiseptics all the time in that stuff we're not challenging your body sort of new system gets bored and if it can't if it can't do the things that it's supposed to do and then it's like well what am I supposed to do I'm really bored here and so what it will now do is say I'll just start attacking itself it gets bored and so I'll just start attacking this so this looks good to attack I'll start doing this and that's where we think some of these other auto immunities are actually happening like Crohn's disease because again maybe it's molecular mimicry or maybe that the immune system in the gut is just not being attacked you know or doesn't feel like it's got enough to do and so it gets bored and now wants to attack itself and so we may see it that way as well and so that's some of possible explanations of why we think we're getting these out immunities now again we get immune system avoidance where and viruses and pathogens can get inside shut down the immune system so that's one way that can happen you can get antigenic variation where again these guys can change by mutations and that again like the flu virus because the flu virus can again change and change its receptors pretty quickly you can go from vanilla - chocolate chip vanilla chocolate swirl very quickly and mutations and that stuff and so that could be an issue of why doesn't get recognized as well as a number of other things and so I'm not going to go through everything here but this is one of the things is that pathogens are smart too and they want to survive and so in order to avoid it they can come up with mechanisms to avoid being attacked and that stuff and that could be one of them being actually shut down the immune system itself now some viruses like I said can go into latency and so that's a problem with a lot of the herpes viruses out there is that they go and hide so once you get infected they then go into latency meaning they hide in the nerve we know this for all really pretty much all the strings or herpes that are out there they go and become latent and they hide inside nerve cells or D cells or other places and then other stimulus is out there like in the case of herpes simplex one things like UV stress fever can trigger it and then it comes out and causes a reaction and so you can see this happening and so what happens is the virus goes layton hides in the nerve and then all sudden you get hit by something that reactivates and then it comes out again and so that's one way to avoid it because if it's hiding the immune system doesn't know it's there if it's just sitting in your DNA somewhere and it's just the DNA of the virus and so especially with the herpes viruses we know that this thing can sit we've known this with HPV and this stuff as well sitting in there and that could be another reason why we don't see attacks on viruses because they don't see it because it's an Allegiant see again another one is HIV and so HIV does attack your t-cells and where it affects again are those cd4 T helper cells and you should and I showed you back in that summary slide how important T helper cells are the activate both the B cells and the T cells when those things may not get it activated on their own and so if you lose that whole system of cells now you can see that it may take even longer for the P and T cells to actually react and you lose a lot of that surveillance system and so if that that's lost now you're going to be more likely to get secondary infections and so most people when they get HIV are not going to die because they lose all their T cells what they're gonna die from is a secondary infection they get from another pathogen that now their T helper cells are gone so they can't activate the system and so things that normally would be no problem for your eye for someone that has severe HIV and a limited number of T cells now can now get infected with it gets sick and potentially die from that because they just don't have the same immune response anymore and that's the problem there another thing is HIV can go into latency it can hide in the macrophages and T cells and so again we know this that some people can be HIV positive and then it kind of go into remission for about 10 to 15 years and then all of a sudden it reactivate and start eliminating those things and so that's why if you've had any risky behavior where you have you think you have a potential of getting HIV you should always get yourself tested because sometimes if you do the test later on you may not see the actual disease because they're the actual virus because it may be hiding at the time and so that's the key and so again you want to make sure if you've been exposed that you do get tested to make sure that you're not carrying the virus itself now again with this the healthy immune system would normally defeat it again we know HIV is either through unprotected sex or again contaminated needles and the infections again HIV can't be cured but the drugs that have developed for basically slow the replication and progression of AIDS and so there's a lot of different drugs that are out there now people that have HIV it's no longer a death sentence they've lived numbers of years we've had people with HIV positive now live for 34 years and again they're on these regimens of drugs but it's keeping them alive and so the key is is constantly getting monitored make sure that there isn't a problem with your t-cells and that if there is that they go make sure that they really kind of established and so one of the ideas with HIV is maybe trying to re-establish that t-helper cell population and people that are losing it and that and looking at ways of doing that and so that's one of the things that are kind of one of those new treatments there's other ones out there like I said you may have read some where they're not showing that they're able to cure HIV out of people especially on children with a certain drug drug protocols and that stuff and so there seems to be some real positive positive ways out there but again there's no vaccine for HIV and so there's always at risk and I think as a population we've kind of gotten last thinking well it's not gonna be a problem because we haven't heard a lot about it but it is still out there so again risky behavior only could set you up with some real big problems later in life so again be safe when you when you do practice or you know when you're out there doing the different things that are out there again being safe about these different things okay and again cancer an immunity this is a last slide I promised and so again cancer and immunity or a big thing because the immune system protects you from again the I'm sorry noon system for actually from cancer and again we see this the difference between a cold tumor and a hot hot tumor cold tumor means that it's invisible to the immune system with no tumor antigens or t-cells or a hot tumor is something that your immune system recognizes and so the idea is to get these tumors that you may have into a hot tuner so that it now recognizes it and then it can attack and destroy and so that's the idea there again with the frequency of cancers when the immunity is impaired so we do see that especially in people like like I said before HIV and that stuff Kaposi's sarcoma is one of the most common ones and again that's spread by a virus a lot of times we do know about fifteen to twenty percent of all human cancers involve viruses and so again that could be an issue and that the immune system can act as a defense against these viruses and again help treat it and so we are now seeing these things to go after after not only the viruses but also to go and activate these t-cells and so that's the other thing getting these cells to be activated to start killing the tumour cells themselves because remember T cells t sort of toxic cells can kill ugly-looking cells and so that's the idea have them sent in and do those things but again you have to look at some markers how are you gonna activate the T cells so they don't go after you and make sure that they have the specific marker and so again personalized medicine looking at all these other things and trying to get this anti-tumor immunity and so it looks very promising if we get the immune system to do its job and do those things then maybe we can eliminate tumors just by doing immunotherapy and much safer and much less time for the patient to actually have lots of side effects in these situations and so that could be the key to the future ok so again we've made it to the end hopefully you get some appreciation of the deaf community serozha long I know I go on these tangents every time you can tell a microbiologist because I spend a lot of time on immunity and that stuff so I think just to kind of get the basics and that stuff I probably could have gone fast and you wouldn't again have to have the information there and that stuff but I just kind of wanted to give you a good sense of what adaptive immunity is and again an adaptive immunity receptors provide the pathogen specific recognition you have the D cells and make antibodies and them ourselves and the effect outside the cells so think of outside they make and secrete these antibodies go and the key is also making memory cells and again so you remember these things and again the T cells attack they attack cells on the inside they also make in memory cells and so they're gonna go after the things inside intracellular parasites cancer cells those things that don't look right and again remember these cells can just activate on their own by floating antigen T cells have our snooty they got to be presented to and so that's gonna be the key the other thing we looked at was adaptive immunity defense against infection of body fluids and body cells we talked about active and passive immunity active is making memory passive is getting antibodies or other forms of immunity in this case to kind of give you a carryover effect to block whatever is causing any infection or whatever but again you make no memory there and then we did talk a number of things about immune dysfunction of what is there where now the immune system doesn't play nice we looked at auto immunities allergies tissue rejection and then potential immune deficiencies that can affect essentially having a last lack of immune so again cancer surveillance or in situations like HIV where you may now lose it announce that you're more susceptible to secondary types of infections okay and with that hopefully you got something out of this if you have any questions and I'm excited and ready to go to answer up for you guys please send me an e-mail or again we can discuss this in class I thank you for watching and I'll see you next time