Pathophysiology Chapter 7: Hypersensitivities

Hypersensitivity - Inappropriate human response to an antigen that results in a pathologic response upon re-exposure What determines whether a hypersensitivity response is an allergy, autoimmunity or alloimmunity? - The source of the antigen Allergy --> environmental antigen Autoimmunity --> host's own cells Alloimmunity --> cells from different host of the same species Define "allergy" and provide 3 examples - Allergy is an exaggerated response against non-harmful environmental antigens. Ex's include hay fever, pet dandruff, gluten intolerance Define "autoimmunity" and provide 3 examples - Autoimmunity is a misdirected immune response against the host's own cells, caused by a disturbance in the tolerance of self-antigen. Ex's include SLE, rheumatoid arthritis, and pernicious anemia Define "alloimmunity" and provide 3 examples - Alloimmunity is an immune response directed against beneficial foreign tissues that come from a different host of the same species. Ex's include immune reactions against transfusions, transplanted tissues, or a fetus during pregnancy. Another way to classify immune disorders caused by hypersensitivity is by the type of hypersensitivity (1-4). How is the type determined? - The type of hypersensitivity is classified based on the immune mechanism that initiates the inflammation and then leads to tissue destruction.