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Unformatted text preview: 1 Immunology Final Exam Review Hypersensitivity hypersensitivity an exaggerated or inappropriate immune response that is not apparent on first exposure but occurs with subsequent contact types of hypersensitivity: [historical classifications] immediate reactions mediated by humoral immunity initiated by Ab or Ag/Ab complex delayed reactions cell-mediated (T helper cells) occur at least 24 hours after exposure more recent classifications: [1963 Coombs & Gell] Type I anaphylactic hypersensitivity mediated by IgE secreted by mast cell response to specific antigens allergens IgE coats the surface of mast cells & basophils subsequent exposure allows cross-linking of the cells & degranulation induce vasodilation & smooth muscle contraction may have a systemic response examples: hay fever eczema asthma anaphylaxis bee stings Type II Antibody Mediated Hypersensitivity cytotoxic kills cells [cell lysis] mediated by IgG or IgM complement Ab involved are directed against cell surface antigens damage is restricted to particular tissues or cell types examples: transfusion reactions T independent antigens Blood Types: A type B Ab B type A Ab AB no Ab universal recipient O type Ab universal donor D Rh +/- Rh + -- have D glycoprotein most Rh when exposed to Rh + blood makes Ab hemolytic disease of the newborn T dependent surface Ag (IgG Ab) mom Rh -; baby Rh + leak of baby blood to mom she makes Ab RhoGam anti-D Ab binds to & blocks D site to decrease moms sensitization autoimmune hemolytic disorders graft rejections autoimmune disorders Goodpastures & Myasthenia Gravis Myasthenia Gravis body makes Ab to Ach receptors & decreases transmission at site Type III Immune Complex Mediated Hypersensitivity does not kill the cell 2 mediated by immune complexes (Ag-Ab) deposition of complexes at various sites triggers activation of serum complement, platelet aggregation, and phagocyte action tissue damage C3a & C5a bind to basophils & mast cells & induce degranulation C5a attracts neutrophils that release degradative enzymes inducing mast cell lysis platelet aggregation can lead to hemorrhage & thrombosis examples: serum sickness with injections of pre-formed antisera Arthus reaction at the site of vaccination painful local inflammatory response post-streptococcal glomerulonephritis secondary syphilis...
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