207_2009_Lect_28TwenEight - 11/23/2009 Biology 207, 2009...

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11/23/2009 1 Biology 207, 2009 Lecture twenty eight Monday, 23 November Immunology - 2 Adaptive immunity a stronger response than innate immunity directed at individual, pathogen-specific macromolecules (antigens) each pathogen is “remembered” by its specific antigen(s) Two main features cell-mediated immunity – killing of pathogen-infected cells by recognition of pathogen antigens on the surfaces of these cells antibody-mediated immunity – effective against extracellular pathogens and their products (e.g., toxins) l l ld l l d/fl id) i it ] [also called humoral (blood/fluid) immunity] Characteristics of the adaptive immune system specificity – the response is directed against a specific pathogen by recognition of unique molecular features of antigens; takes some days to develop; based on specific antigen-antibody or antigen-immune cell (T cell) interactions. memory – second exposure to an antigen seen before stimulates rapid production of antigen-reactive T cells or antibodies; allows host to specifically resist previously encountered pathogens; immunization against a disease (vaccination) is based on immune specificity and memory. tolerance – the acquired in ability to make an adaptive immune response to one’s own antigens; immune system discriminates between antigens that are foreign (nonself, dangerous) and host (self, not dangerous); tolerates (does not attack and destroy) self. definitions ntigen – molecule (e g omponent of the cell of a pathogen) that antigen a molecule (e.g., component of the cell of a pathogen) that interacts with the immune system antigenic determinant [also called “epitope”]– that portion of an antigen that interacts with (binds to) an antibody (immunoglobulin) or a T cell receptor T cells and B cells – cells of the adaptive immune system) special types of leukocytes called lymphocytes T cells (T lymphocytes) – cell-mediated immunity
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207_2009_Lect_28TwenEight - 11/23/2009 Biology 207, 2009...

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