let's discuss the maturation and actions of subsets of helper t-cells there are three main classes of T lymphocytes or T cells including cytotoxic T cells which directly kill host cells that are infected by microbes T regulatory cells which suppress the immune response by inhibiting helper T cells dendritic cells and cytotoxic T cells and helper T cells which help activate other immune cells like macrophages dendritic cells cytotoxic T cells and B cells this video focuses on subsets of helper T cells when an ID helper t-cell encounters a presented antigen in peripheral lymphoid tissue it becomes activated and differentiates into a particular subtype of effector helper t-cell determined by the type of cytokine released by the antigen presenting cell subtypes of effector helper T cells include T helper 1 T helper 2 and T helper 17 the type of cytokine released from the antigen presenting cell is determined by the type of antigen that activated the naive helper T cell as well as the type of antigen presenting cell that activated the naive helper T cell now activated these effector helper T cells can then activate other cells to generate a particular immune response if the antigen presenting cells secretes the cytokine il-12 the naive helper T cell matures into a t1 helper cell the helper T once Alvin secretes the cytokine interferon gamma which activates macrophages and causes B cells to produce IgG antibodies which are important in activating the classical complement pathway and for opsonization of microbes helper t1 cells are also the subtype that activates cytotoxic T cells helper t1 cells play an important role in immunity against intracellular microbes including mycobacteria over activation of helper T one is involved in type 4 hypersensitivity reactions the cytokine il-4 released from mast cells causes the naive T cell to mature into a helper T to sell the helper T to selves and secretes aisle 4 to simulate B cells to secrete IgE antibodies aisle 5 to activate eosinophils and aisle 13 to stimulate mucosal epithelial cells to produce mucus helper T 2 cells are important for immunity against large multicellular pathogens like parasites including Hellmann's and are predominant in allergies atopic individuals that are prone to allergies have a greater helper t2 to t1 ratio and therefore higher amounts of IgE over activation of helper t2 is involved in type 1 hypersensitivity with secretion of aisle 6 and transforming growth factor beta the naive T helper cell will mature into a T helper 17 which will produce aisle 17 to recruit phagocytic cells like neutrophils and macrophages to tissues that are infected with certain extracellular bacteria and fungi helper T 17 plays an important role in the defense against extrasolar pathogens this regulation of helper T 17 is involved with many autoimmune and inflammatory disorders including inflammatory bowel disease multiple sclerosis and psoriasis now for some questions if you answer the following you are correct and some more questions if you answer the following you are correct thanks for watching