PSL301H1 Lecture Notes - Lecture 3: Antigen, Cell-Mediated Immunity, Iges
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PSL301H1 Full Course Notes
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Document Summary
Acquired immune responses are antigen-specific responses: body recognizes a certain foreign substance and reacts specifically against it. Mediated primarily by lymphocytes: active immunity. Occurs when body is exposed to a pathogen, then produces its own antibody. Can occur when a pathogen naturally invades body, or via vaccination: passive immunity. Occurs when antibodies are acquired from another animal. 3 main types of lymphocytes: cells can be distinguished from each other by their specific membrane receptors. Lymphocytes specific to a give ligand known as a clone. Each clone of lymphocytes is represented by a few cells, na ve lymphocytes: continue to be generated throughout lifetime, first exposure to antigen activates appropriate clone, stimulates clonal expansion, differentiate into effector and memory cells. Subsequent exposures to antigen activate memory cells and enhance subsequent response efficiency. Few memory cells of clone remain behind after antigen has been repelled, in preparation for next response.
