good morning dear students for today's lecture i will be discussing about the complement system so what is a compliment uh compliment is part of the natural immunity or the innate immunity and it is actually an important effector in both the innate immunity and the acquired immunity so in other words although it is discussed as part of the init immunity but it bridges the gap between the init commun init immunity and the acquired immunity now the complement forms the complement proteins form the so-called the complement system so this is a collection of the different complement proteins so the complement proteins are natural serum constituents okay so in complement this is a natural serum constituent so in other words it is present in the blood plasma or in the serum okay it's present it is a protein that is contained in the serum or plasma and this protein will increase in concentration if there is inflammation okay so there are about 30 circulating and membrane bound proteins that composed our complement system and these 30 over 30 circulating and membrane bound proteins are synthesized by the hepatocytes and other cells immune and epithelium cells okay so almost all complement proteins are synthesized by the hepatocytes those that are synthesized by other cells are the c1 factor d and din and c7 complement seven so c1 or complement one is produced by the intestinal epithelial cell so again your complement one or c one is compo is produced by the intestinal epithelial cell factor d this is produced by the adipocytes or adipose cells and then um c7 or complement seven and proper din these two are produced by monocytes or macrophages neutrophils and t cells okay and then majority are produced by the liver cells okay now the complement proteins in the complement system will act as a cascade so when we say cascade mechanism so it's similar to the coagulation pathway we're in one event must take place before another event takes place okay so when we discuss the activation you will realize why is it why is it um considered as a cascade system okay because the activation of one component will lead to the activation of the other component okay so it's a cascade mechanism okay so let's um trace the history of the discovery of the complement system so scientist who contributed in the elucidation of the role of the complement system was erlich so according to erlich um he explained the role of complementing antibodies in terms of killing of bacteria so back then hindi patalaga [Music] discovered the activity of the complement in the serum sample so he said that there is this substance that complements antibodies okay so there is the substance complementing the antibodies in terms of killing of bacteria and then another scientist is boarded uh where that elucidated the role of a complement okay so complement is not only acting as a complementing protein for the antibodies in terms of killing the bacteria so it also performs other role aside from being an optioning okay aside from being an obsolete so veranti chang other rule aside from being an option which we'll discuss later on okay now based on their findings uh they they realize that these complementing proteins present in the [Music] in the plasma or serum is heat labile okay so this protein is heat labile so when we say heat labile it is destroyed by heat so they they play also with the temperature they they heated the serum sample and then and then they found out that kapagnaging serum sample the the complementing the complementing uh protein becomes inactivated okay so activity in applying heat in the serum sample but those uh sera or blood samples that were not heated so the activity is intact okay so therefore the complement is said to be destroyed by heat or heat level or sensitive uh to increase in temperature okay and then after their their contribution they there is a subsequent discovery of the different complement components okay so current knowledge says that there is more than 30 proteins in the plasma some are membrane bound okay and five percent of the globulin fraction of proteins our complement so the complement will particularly so this is our abbreviation for complement so complement will will be isolated from the beta globulin region in a serum protein electrophoresis diba pugna performed spe this is positively side electrode this is what you will get so this is albumin and then globulin so no fibrinogen because fibrinogen has been consumed in the coagulation process so the globulin fraction is divided into several fractions the b the alpha 1 alpha 2 globulin beta globulin and then the gamma globulin okay so this is the negative side okay so you isolate the complement here in the beta globulin region okay so little isolation complement the gamma globulin or the antibodies are found here in the gamma globulin region okay in serum protein electrophoresis so let's move on to nomenclature how do we name the complement proteins so to name the complement protein we use capital letter c and then followed by number so c1 c2 c3 you know in c1 c2 c3 etc okay so that's how we name the complement proteins now the c1 the c1 is further composed of different subunits c1q c1r and then c1s okay now the c1 is considered as the recognition unit okay so this is described as the recognition unit and then activation unit so after my recognize okay there will be activation the activation unit uh is composed of the c4 c2 and c3 okay c2 c3 c4 so those are the activation units while c5 6 7 and 8 and 9 so this is called the membrane attack complex unit okay or until downloading mac complex or mac unit okay now um the complement proteins are referred to as zymogens so they are called zymogens when they are still inactive or intact okay activation complement protein it will be cleave into two products okay so there is this formation of the cleavage products and the cleavage products are designated as a and then b okay so for example activation c2 there will be formation of c2a and c2b so c2 if not yet activated so this is a zymogen when it becomes activated it will become a serene protease okay it will become acetylene protease and there will be formation of two cleavage products c2a and c2b okay so this is just to give you an example so later when we discuss the the activation the different pathways of activation so you will see what will happen in the different complement proteins okay now the complement proteins are are bind will bind to the receptor okay and we call this the complement receptors so these are these are the receptors for complement okay so the one that will bind to the complement proteins now the complement receptors are named according to the ligand for example complement receptor 1 complement receptor to etc or using a cluster of differentiation system so humana cr1 cr2 these complement receptors have equivalent cd number okay so they have an equivalency number so cr1 or complement receptor one obviously will bind c1 cr2 or complement receptor two will bind c2 etc okay so that's what that's how we name the complement proteins as well as the receptors okay so another thing about the complement um is that the order of discovery of proteins is different from the order of activation okay so your order of discovery is as follows c1 followed by c2 c3 c4 etc up to c9 okay so that's how complement proteins are being discovered so in order of discovery now in terms of activation the activation is different order of activation is c1 okay followed by c4 c2 c3 okay c5 c6 c7 c8 and then c9 okay so that is the order of activation okay so you know uh things that you need to know about the nomenclature about the complement system now let's move on to the four important functions when the complement system is activated it will lead to cytolysis okay so there will be bursting or destruction of the target cell okay so there will be lysis or bursting or destruction of the target cell and then another consequence or function of complement activation is optionalization so you are familiar with the term optionalization this is also called facilitated phagocytosis okay facilitated phagocytosis so this is a way to immobilize a certain mobile cell so for example bacterial cell okay so immobilize young bacterial cell by means of complement proteins so that the phagocyte can can easily move and phagocytize the that specific target cell okay so immobilize complement human mobile cells so that the phagocyte can run after the target cell okay that is facilitated phagocytosis or optionalization and then another important uh function is the activation of inflammatory response okay so it will trigger inflammation it will trigger anaphylaxis okay and another is clearance of immune complexes okay clearance of immune complexes now um there are times wherein there is too much production of antigen antibody complexes so combining antigen and antibody we call that antibody antigen antibody complexes also known as immune complexes okay so this antigen and antibody complexes that are in excess has to be removed has to be cleared by our immune system or else they will deposit to the tissues of the body and cause destruction of the tissues okay so the phagocytes particularly the eosinophils can clear the antigen antibody complexes by by means of the help of the complement system okay so this is lysis and so complement will cause hole holding onto the target cell membrane okay causing the target cell to burst or or or there will be cytolytic action okay target cell and then another is optionalization okay so some bacterial cells are tagged with complement okay complement will stick young red represents the complement that will stick onto the bacterial cell membrane and so as a result the phagocyte can easily engulf the bacterial cell that is obsoletion okay so another function of complement is the activation of inflammatory response so some complement proteins will will be attached onto the surface of the mast cell or basophils causing the mass cells to the granulated so we all know that one of the one of the granules inside the muscle is a vasoactive amine okay sombrero is active by mine and that will trigger inflammation okay so that will trigger inflammation and then lastly clearance of immune complex so the antigen antibody complex is tugged with a complement protein okay so that the phagocyte or eosinophil can easily clear this immune complexes so that they won't get deposit in the tissue the host tissue destruction okay so let's move on to the three pathways of activation so the activation of the complement system is done in either classical pathway alternative or alternate pathway and the lectin pathway okay so take note that these three pathways are different in the start then start now [Music] activation okay so they differ in the start of the system activation but in the latter part they will enter unidentical in the final steps there will be an identical pathway in all these three pathways so parang is a complement paranoia complement system pattern coagulation system okay so wherein there is um intrinsic pathway for the coagulation system there is intrinsic pathway and extrinsic pathway but later on the intrinsic and the extrinsic pathway will merge forming the common pathway okay so different pathways classical alternative or alternate and then lectin pathway so all these three will merge in the final steps so there will be an identical step in these three pathways okay so classical pathway is initiated by the formation of an antigen antibody complex okay and then alternative pathway is said to be antibody independent okay antibody independent because it does not need an antigen antibody complex or an immune complex to be activated okay so this is part of the init immunity however for the classical pathway so it bridges the gap between the innate and the acquired immunity because this is triggered by antigen antibody complexes and this antigen antibody complex is specific okay so specific [Music] immunity or acquired immunity okay so alternative pathway is initiated by foreign cell surfaces and then the lectin pathway is initiated by proteins mannose or man and binding microbial surfaces okay so a microbial surface there is a mannose carbohydrate okay so cell volume bacteria mannose carbohydrate so this manners um carbohydrate will be detected by the mannose binding lectin okay so this will be detected or or this will bind to the manus binding lectin or the mbl okay and that reaction will trigger the activation of the lectin pathway okay so we have here a diagram showing the classical lectin and the alternative pathway so as i have said earlier starts initial so initial um steps they differ these three pathways differ okay but they will enter a common final step okay so the three pathways will merge in a common uh final step okay take note that the classical pathway is triggered by antigen antibody complex okay and that will uh lead to the activation of the c1 followed by the activation of c4 and c2 okay to form the c3 converters ctrl converters will cleave the c3 molecule okay and then eventually c5 converters will be will be formed c5 convert this enzyme will cleave the c5 okay and then it will enter now the membrane attack complex so c5 will split into two products c5b will bind c67 and then 9 to form the membrane attack complex now for the lectin pathway the manus binding lectin which is part of your natural immunity will detect the microbial cell world because the microbial cell will has manus okay and as a consequence the mass will be activated leading to an activated c1 like complex okay so as a result the c4 c2 will be activated and then there will be formation of the c3 converters which will cleave c3 to c3 a and c three b okay so c three b will join the city converters complex to form the c5 converters and then c5 will cleave into two products e5 and c5b when c5b is formed it will attach to 6 c6 c7 c8 and then c9 okay and then for for the alternative pathway this will start in the activation of c3 molecule okay so this will start in the activation of the c3 molecule so in other words um the alternative pathway is a bypass person bypass pathway so why bypass young c1 um c4 and c2 okay c3 activation so if c3 is activated this will lead to the formation of the c3 converters and then eventually there will be formation of the c5 converters so c5 will cleave into two products the c5b will will bind to c6 c7 c8 and then c9 so yuma gigging final pathway okay so c3 is considered as the pivotal so you you young activation of the c3 is said to be the pivotal pathway in all the three pathways okay so your activation of c3 this is the pivotal of that the pivotal uh step in the tree among the three pathways okay so let's start let's now discuss the details of the classical pathway so again this is antibody directed mechanism because the the pathway will that the activation of this pathway requires presence of antigen and antibody complex okay so the there are several kinds of antibodies iga g m igg igd ige okay so take note that not all these antibodies will activate the complement via classical pathway okay so long the igm and then the igg okay only the igm and igg so ige iga igd cannot activate the complement via classical pathway okay so igm is a more powerful complement activator as compared to the iggs so obviously because it is a pantomimeric it is a pentamer in structure while the igg is a monomer in structure okay now uh there are three there are four subsets of iggs igg one igg2 and then igg3 okay so igg4 cannot um activate the complement pathway the classical pathway okay so only the three igg one igg2 and then igg3 now among these three iggs the igg3 is said to be the most powerful complement activator okay among the three iggs peroxia premise must powerful activator perennial ig and because of its structural pentametic structure okay so uh followed by igg-1 followed by ig2 okay so ig2 and ig4 both have short hinge less powerful in [Music] less efficient in activating the complement okay so therefore they are considered as poor activator poor complement activator now the igg3 has longer hinge region so therefore it is a good activator of the classical pathway so aside from those antibodies other other things that can activate the classical pathway is crp serious protein some viruses mycoplasma trypanosomes so this can also activate the complement via classical pathway and then three stages um consists of the following units the recognition you need the activation you need and then the membrane attack complex i have discussed this earlier so let's start with the recognition you need okay so this is how a c1 molecule looks like okay so meronshang head and so this is the head part and then this this is the stock okay the young stock so this is c one q this is c one q you my head and stock okay so the head can bind to the ch2 domain constant heavy chain uh two so remember the antibodies variable region followed by the constant region so ch1 ito and then ch2 so h1 ch2 ch3 for the igm igm is longer meron ch4 jung igm okay mehang ch4 that's why it is considered as a complete antibody but in the case of igg igg molecules are shorter because up to ch3 lanzilla your constant region okay so the the head of the c1q molecule binds to the ch2 domain of antibody so this is true for igg but for igm molecule the head of the c1q will bind to the ch3 portion because extra energy h4 so for igm uh the head of the c1q will bind to the ch3 constant heavy uh chain region number three okay now the c1 q consists of collagen like triple helix okay so this is the head this is the stock part okay and take note that the c1q consists of six globular units okay so six globular units okay one two three four five six nancy sodium stock in this in this electron micrograph picture okay so aside from c1q another component of the c1 are the c1r and then the c1s okay so this is c1r and c1s are similar to figure eight appearance stock okay so you want your new arrangement number c1r and then c1s so when the c1q attaches to the antibody particularly to the ch2 or ch3 of the antibody it will lead to the activation of c1r and then it will lead to the activation of c1s so that will be the start of the recognition okay so when c1r and c1s will become activated there will be generation of enzyme activities that will begin the cascade okay so let's move on okay so let's move on to to the classical pathway so again this is initiated by the formation of soluble hydrogen antibody complex okay so let's say c1q you see one queue uh not recognized sanyayung antibody so that will lead to the activation of the c 1 r and c 1 s okay so this is the okay for a while but i am operating screen can you see the transition of the slide i am okay okay so let's move on okay so this is the c1q molecule so again you'll see one the c one q is the one that will recognize so you can see one queue is the one that is responsible for the recognition so it will young head this is the stock okay so now there are two c1r under r2c 1s components okay now for example this is your target cell okay uh these are the antigens present on the target cell so there will be antigen antibody complex okay so this immune complex the the c1 q head will particularly bind to the ch2 or ch3 antibodies okay so when the head of the c1q recognizes the the ch2 or ch3 portion of the antibody binding the target cell so there will be activation so when you see this bar line it means activate your component okay so there will be activation of the c1 r2 and then activation of the c1 s2 okay so when this activates this component activates uh this will start the the activation this will lead to the activation of the c3 component okay and so the activity on c1 r2 and c1 s2 so the c1s will cleave the c4 and then the c2 molecules okay so at first c4 is an intact complement when c1s act on the c4 molecule the c4 will break into two pieces okay so it will break into two pieces so c4 will break into two pieces there will be formation of two pieces c4a and then c4b okay so same will happen in the c2 molecule at first it is intact when c1s acts on it activated c1s acts on it it will break into two pieces c2b and then the c2a okay so take note that the c2a and the c4b molecules will bind together okay so the c4b and the c2a portions will bind together forming now the c3 converters so this c3 converters will now cleave the c3 molecule okay so you some portion will go to the plasma and perform other functions like anaphylatoxin obsonine etc okay so now that we have the c3 converters so the c3 converters will cleave the c3 molecule so c3 now will will the intake c3 now will break into two pieces okay so there will be formation of the c3b and the c3a um cleavage products okay so the c3b will bind to the c4b 2a to form c4b2a3 okay so this complex will now become our c5 convert this okay so c3a will go to the plasma and perform other functions okay so now that we have the c5 converters yeah and so c5 converters will cleave the intake c5 molecule okay so it will cleave the c5 molecule into two pieces what are these pieces the c5b and then the c5a c5a goes to the plasma and it becomes an anaphyla toxin the c5b now will lead to the activation of the membrane attack complex okay so notice here that the c5b will bind to the c6 and then it will bind to the c7 and then the c8 forming the c5b 6 eight okay so palmer nancy phi b six seven eight this will penetrate now the target cell okay cell membrane okay and then eventually c9 will join the complex so c9 will join the complex forming hole onto the target cell okay so pug c5b678 cell membrane it will cause crack onto the cell membrane okay but the successful holding will be done when the c9 polymerizes the the complex the cell membrane complex okay so there will be formation of hole onto the target cell okay so that can cause cytolytic action yeah magnetic polymerization because of the c9 okay for foreign so that is classical pathway okay so let's now move on to the alternative pathway uh so this was first described by p lamer and this is the bypass pathway because there will be no activation of the c1 there will be no recognition of by the c1 uh no activation by the c2c4 so c3 again okay it's a alternative pathway starting on c3 activation okay uh followed by through the help of the factor b factor d and then the proper dean okay so take note here that the proper dean does not initiate the pathway but instead it stabilizes the c3 so again it does the proper din does not initiate uh alternative pathway but rather it stabilizes the c3 converters okay so triggering substances may be pathogens or non-pathogens like bacterial cell wall components fungi viruses parasites and two more cell lines okay so we have here the list of um activators of the alternative pathway so there are pathogens and particles of the microbial uh or of microbial origin and there are none pathogens okay okay so let's start with the what will happen in the alternative pathway activation okay so it will start in the hydrolysis of the c3 molecule okay so young c3 is not a stable component in the plasma so when water is present it will hydrolyze the thio ester bands of the c3 so as a result the c3 will when it hydrolyzes there will be formation of two components the c3b and then the c3 a okay and then c3b will bind the c3b binds to the factor b okay so after mug binding c3b to factor b factor d will act on this complex and what will be the action of the factor d the factor d will cleave the factor b to form b b and ba split products okay so the ba factor b a split products will go to the plasma while the bb and well the factor bb segment or cleavage product will will bind to the c3b forming now the c3 converters okay now the c3 converters must be must be preserved so you have life casino city converted is just very short so to be able to prolong the life of the city convert is it has to be stabilized by proper dean okay stabilizer stabilizatory converted so prolong young life thanks to converters and so more c3b can add up to the complex okay so remember continuous demand casino hydrolysis nang c3 so some c3b can join now the c5 convert will will now join the c3b bb complex okay if this stabilized by proper din forming down the c5 converters so now that we have the c5 converters it will cleave the c5 to c5b and c5a and then c5b now will will now activate the membrane attack complex okay so c6 c7 c8 and then c9 followed by the c9 so same effect but different in the pathways of activation okay so that will happen in the alternate or alternative pathway so now let's move on to the lectin pathway so the lectin pathway is initiated by the binding of the manus from the bacterial cell wall with the mbl mannose binding lectin okay so mannose or mana binding lectin so this will bind to the mannose on the bacterial cell and mbl is produced by the liver in acute phase inflammatory reactions so mbl is part of your innate immunity okay or natural immunity okay now uh mbl will bind to the target cell because the target cell has manus and then there will be activation of the serine proteases mass 1 and mass 2 okay so your mass stands for mbl associated mass stands for mbl associated serine proteases and they correspond or or they are analogous to the c1r and c1s okay so your mass point this is analogous with c1r mass 2 this is analogous to c1s okay clear yeah so mbl it acts as if it is a c1q molecule okay so c1q will bind to the parashang analogue c1q so the mbl binds to the manus and then eventually mag mag activate your mask one and the mask which are analogous to c1r and then the c1 s okay so when when the mast one and the mask 2 are activated so they will this will lead to the activation or this will lead to the activation of the c4 and then the c2 okay so this will lead to the activation of the c4 and then c2 okay so when c4 and c2 are activated they will split and then eventually mug foreign so c3 now will be activated there will be formation of c3a and c3b split products i'm gonna activate the bimx split so there will be formation of c3b and then c3e so c3b will join the complex for means c4b2a3b so this is now your c5 converters and then this will now lead to the activation of the membrane attack complex okay so there will be formation of 6 c5b 7 c 8 c 9 will join c5b okay forming holes onto the target cell okay so let's now move on to the regulation of the complement system uh take note that there are although although we discussed the functions of c1 to c9 in the activation but as i have said earlier there are over 30 proteins because the other proteins will act in the regulation process okay so because the complement system is non-specific in action uh you need a regulatory mechanism to be able to prevent collateral damage okay so remember that the components are very labile and these regulatory proteins are needed to be able to block the activity through binding to the target okay so animal regulators of the complement system so take note there are proteins that regulate assembly of the converters activity okay so there are proteins or complement components that that prevents assembly of the converter's activity so of course bhagwalang c3 converters or c5 converters uh hindi push through your activation okay but let's say the converters have been successfully made there are still proteins that can uh act after the assembly of the converters and there are also regulatory molecules or proteins that will that will prevent assembly of the membrane attack complex okay so those that will act before before the assembly of convert is activity we have the c1 inhibitor okay so obviously it binds c1 [Music] r2 s2 causing the c1 r2 s2 to dissociate so tatangalino c1 inhibitorium c1 r2 s2 it will dissociate this molecule uh from the c1q so there will be no activation of the c4 and c2 okay so at another is association of c4b 2a so c4 b2a will form the c3 converters so this will be blocked by binding c4b binding protein and complement receptor one or membrane cofactor protein okay so young c2a and c4b instead number binds in that to form the ct convert is the c4b will be confiscated by c4b binding protein complement receptor one or mcp membrane cofactor protein okay so when c4b na gao sa c2a okay there will be no formation of the c3 converters okay so c4b now will be acted upon by factor one and uh it will cleave the c4b to c for c and c for d okay so that while ana talagang c3 converts that will be forming okay and then in the alternative pathway complement receptor 1 mcp and factor h prevents the binding of the c3b and factor b so there will be no converted activity so further the c3b is acted upon by factor one to make it inactivated okay c3f or inactivated c3b and then eventually it will be broken down into two pieces c3c and c3dg okay and then after the assembly of ct converter so let's say let's say successful young converters formation c4b binding protein complement receptor one factor h and daf daf stands for decay accelerating factor so this duff will dissociate uh will cause dissociation of converters remaining c4b or c3b and then it will cleave by factor one and then in the membrane attack complex these are some examples of regulatory proteins the s protein the hrf hrf stands for homologous restriction factor and then the merle or the membrane inhibitor of reactive lysis also known as cd59 okay so the s protein will bind to the will bind to the c5 b67 to prevent it from binding to see it okay so there will be no insertion onto the cell membrane and then for the homologous restriction factor membrane inhibitor or merle uh they will bind to the c5b678 complex okay so there will be no complex that will attack now the cell membrane or cause breakage of the cell membrane okay so these are the summary of the regulators so factor eight h acts by binding c3b c3b has has a 100 fold greater affinity for factor h than factor b so factor h will act as cofactor to factor one to break down c3b s protein this is also known as vitronectin so again it will bind to the c5b67 to prevent it from insertion or binding to the cell surface okay so same with mir uh or cd59 it will prevent c9 uh to bind to c8 so there will be no holding effect on the target cell membrane okay so these are the biological rules of some complement receptors so complement receptor one also known as cd35 this is a cofactor to co-factor factor one cr2 also known as the cd21 so this is a b cell co receptor for antigen with cd19 okay so we don't cd21 this is the reason why epstein-barr virus gains entry to the b cell so you've learned that in virology okay so the epsilon bar virus will attach to the cd21 of the b cell so yeah epsilon bar virus infection cannabis okay because of the cd21 which is the gateway of the of the epsilon barbarus to the s to the b lymphocyte and then complement receptor 3 also known as cd11 or cd18 promotes adhesion and increased activity of phagocytes cr4 also promotes adhesion and increased activity of the phagocytes okay split components one of the split components goes to the plasma and as i have said it will perform other functions okay so this table will just show you the different biological effects mediated by the complement products okay so take note here young c4a uh c3a c5a they will become anaphyla toxins okay c5 a and c3a will will they granulate the aoc in the field so they will trigger [Music] the granulation of aocenophils so what else c5a c3a can act as a chemotoxin okay so when we say chemotaxin parashaan chemical messenger that will recruit leukocytes at the inflammation site okay so tata mangalyokocytes to go to the site of inflammation because of these split components of the complement so some will become optioning so they will facilitate phagocytosis okay so others will promote viral neutralization and solubilization of the clearance solubilization and clearance of immune complexes okay so that means that means you one of the split components although it will not bind to other complements but they will perform other functions okay they will mediate some biological functions okay so cell lysis some will become an affilotoxin chemotaxin and opsinine okay others will become [Music] complement proteins that will mediate facilitated phagocytosis okay and solubilization of the immune complexes okay solubilization of the immune complexes okay so let's move on to the association of some diseases to complement okay so let's say the regulation regulatory proteins are not working well or for example there is over activation of the complement system so that can cause damage to our body okay so complement can can be harmful if they are activated systemically on a large scale as in gram-negative septicemia okay so it is also harmful when it causes tissue necrosis or if it causes lysis of red blood cells okay so complement if they are deficient can also become harmful for the body so everything that is in excess and and insufficient is also bad for the body okay so example if c2 is deficient that can lead to arthrosclerosis recurrent strep and staphylococcus infections if c3 is deficient so this is the most serious because c3 is the most abundant complement component and this is the pivotal complement component so this can lead to streptococcal infections and immune complex diseases and then c5 to c9 if they are deficient so deficient human membrane attack complex there will be neisseria infections mending cochocal meningitis and disseminated gonorrheal disease so at risk infection ion if these complements are deficient okay if the decay accelerating factor is deficient so you are at risk of paroxysmal hemoglobin so your rbcs are prone to hemolysis if the c1 inhibitor is deficient that will make one prone to hereditary angioedema okay and then for the laboratory diagnosis this will be discussed in your laboratory but just to give you an idea uh the tests for complement proteins are grouped into two measurement of components as antigens in the serum and the measurement of the complement functional activity okay and then these are the different laboratory tests uh radial immune diffusion technique so formula agar tapos agarose gel you deliver in the hole or in the well the complement the serum which contains a complement okay so meron anti-c3 in this agarose gel so the the you allow the serum to diffuse and there will be formation of precipitating ring and then you measure the ring size the diameter of the precipitating ring and then that has an equivalent c3 concentration test that is radial immune diffusion okay so the details of this will be discussed in the laboratory and then flowmetri this is coupled by automation and we also have hemolytic titration assay or the ch50 assay in ch 50 assay we measure the amount of the patient serum required to lice 50 of the standardized concentration of antibody sensitized ships rpc okay and then elisa enzyme linked assay so another lab test is the ah50 assay so this is the the ch 50 is for the classical pathway if you want to to determine the functional activity of the components under the classical pathway if you want to determine the functional ability of the components complement components in the alternative pathway you do the eh 50 assay so basically same language procedure except that in ah 50 assay you add something to the buffer you add magnesium chloride and ethylene glycol tetracetic acid to the buffer okay so this will block the classical pathway activity so therefore you you measure only the functional activity of those components in the alternative pathway okay and then complement fixation test okay so complement fixation test uh your complement fixation test this is a traditional test to to determine presence of antibodies in the serum sample okay so this is divided into [Music] two phases the bacteriolytic phase and the hemolytic phase okay so the lung phase is your bacteriolytic phase and the hemolytic phase okay so complement fixation so as i have said bacteriolytic phase and then hemolytic phase yuma faces so this is what happens in the bacteriolytic phase okay so there is a bacterial cell reagent so fogbini lemon test a bacterial cell reagent so obviously it has antigens on the surface okay now in your patient see room you want to find out if there are antibodies in the serum okay so if the antibodies are present in the serum you add it to the bacterial cell reagent so there will be formation of antigen antibody complex okay and then you add now guinea pig serum the guinea pig serum is the source of complement okay so this is a source of complement so complement will be fixed here it is hd or ch2 portion of the antibody okay so complement is fixed here so the next phase is the hemolytic phase in hemolytic phase you add now the indicator cells okay so you add shapes rbc suspension okay so what will happen if the compliment is fixed because of the presence of the antibodies so the complement will not attack the the ships are busy okay uh sensitized by antibodies so memory ships are busy sensitize with antibodies okay so the complement will not attack the sensitized ships are bc okay so there will be no hemolysis so therefore no hemolysis is considered as a positive reaction so positive uh in the sense that the antibodies are present in the patient's room okay but if you if you omit the antibodies in the patient serum so let's say absent antibodies so what happens bacterial cells are free okay on its surface so the complement is also floating in the system so if you add now the shapes rbc sensitized by antibody the complement will attach here causing hemolysis okay on your rbcs so when our bases are hemolyzed that is an indication of negative reaction so negative that means antibodies absent your antibodies in your patients room okay so that's how we perform complement fixation test so this will be further discussed in the laboratory okay so do you have questions before i dismiss you