Type of T-lymphocyte CellsFunctionT-cytotoxic cells Differentiation of T cells into effector cells -Activated by various cytokines -Attack and kill targets directly by release of cytotoxic chemicals which destroy the cell membrane or induce apoptosisAKA cellular immunityoTargets: cells infected by viruses, cancerous cells, allograft cells(transplant tissue)-CD 8 cells (AKA Killer T’s, T8 cells)NK Killer cells Recognition and elimination of cells infected with viruses-Eliminate abnormal host cells (specifically cancer cells)-Inhibitory and activating receptors that allow differentiation between infected/tumor cells & normal cells -Binds to target cell through activating receptors > produces several cytokines & toxic molecules that can kill the targetT-Regulatory cellsSlow/stop immune response once the invader is defeated-Prevents against attacking self-antigens & avoid over activation of the immune responseT-Helper cells Facilitate immune responses by secreting chemical messengers (cytokines) which stimulate differentiation of B cells into plasma cells (anti-body producing cells)
AKA CD4 cellsoFunction to activate macrophages (B cells, cytotoxic T cells & other CD 4 cells)Release lymphokines that begin the inflammatory process & mediate delayed hypersensitivity reactions (ie: TB skin test)-Functions are performed by the subgroup of CD4 cells TH1 and TH2Memory T-CellsAllow host to remember antigens & respond quicker/more vigorously after initial exposure-Live for many years, can reproduce themselvesType of CellRole in the Processing of Antigens B-LymphocytesT-lymphocytesAntibody circulates in the blood & binds to antigens on infectious agentsoResults in: direct inactivation of the microorganisms or activation of a variety of inflammatory mediators (ie: complement, phagocytoes) that willdestroy pathogenPrimary immune response: On initial exposure to most antigens, there is a latent/lag period during which B-cell differentiation and proliferation occur. Approx. 5-7 days, IgM antibody specific to that antigen can be detected in circulation. Lag phase is result of time necessary for clonal selection, including processing & presentation of antigens, induction of Th cells, interactions between immunocompetent B cells and Th cells, and maturation & proliferation of B cells into plasma/ memory cells.Secondary immune response: More rapid production of a larger amount of antibody than that produced by the primary response. In result of the presence of memory cells that do not require further differentiation. oSame amount of IgM produced in primary as in secondary. oIgG production increased- predominant antibody for secondary response, may remain elevated for extended period of time (esp. if antigen in form of vaccine/ natural infection)Aging and the Immune System
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