5b. Acquired Immunity

5b. Acquired Immunity - 5. Human Host Defenses Against...

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    5. Human Host Defenses Against Parasitism: Acquired Strategies - Acquired Immunity
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    2 Third-Line Defenses Acquired Immunity Acquired Immunity acquired immunity : resistance acquired against specific antigens antigens : chemicals that elicit a response by the body’s immune system (abbreviated Ag) important features nonself : not normally found in one’s body immunogenic : stimulates production of immune cells reactive : can react with immune cells or their products
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    3 Third-Line Defenses Acquired Immunity diverse nature: milk proteins insect venom blood components organ transplants microbial components
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    4 Acquired Immunity Antigens typically macromolecules : large complex chemical compounds generally > 10,000 molecular weight (measured in daltons, hydrogen molecule is 1d) chemical composition (ranked strongest to weakest antigenically) protein - largest array of building blocks polysaccharides (capsule, A and B blood group Ag) weaker due to lack of chemical diversity DNA and lipids are poor antigens - limited diversity The number of building blocks and the size contribute to the likelihood of a unique combination of building blocks being present in the Ag
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    5 Acquired Immunity Antigens epitope : a unique site on antigen which is recognized ~6-8 amino acids or carbohydrate molecules long antigens typically have more than one epitope (many) hapten : a small molecule that complexes with self molecule to form Ag acts as epitope (e.g. penicillin combines with self protein allergic response)
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    6 Acquired Immunity Antigens Specific Immune Tolerance immunity theory proposed by Burnet and Talmadge (1957) person’s own protein and polysaccharide do not stimulate immune response (interpreted as “self”) before birth, potential Ags contact and inactivate immune system cells that might respond to them becomes tolerant to “self” and respond only to “nonself”
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    7 Acquired Immunity Antigens Specific Immune Tolerance immunity theory proposed by Burnet and Talmadge (1957) person’s own protein and polysaccharide do not stimulate immune response (interpreted as “self”) before birth, potential Ags contact and inactivate immune system cells that might respond to them generates a repertoire of lymphocyte clones, each with unique receptor display becomes tolerant to “self” and respond only to “nonself” Receptors Lymphocyte stem cell Self Self Eliminated clones
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    8 Acquired Immunity Antigens Types of Antigens autoantigens : “self” Ag that elicit an immune response basis of autoimmune disease alloantigens : Ag found in some but not all members of a species ABO blood group Ags Rh Ag tissue-typing Ag (MHC - major histocompatibiity complex)
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    9 Acquired Immunity Cells of the Immune System Blood Components serum : fluid containing minerals, salts, proteins plasma : serum containing clotting agents cells : (from bone marrow) red blood cells white blood cells platelets
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5b. Acquired Immunity - 5. Human Host Defenses Against...

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