MICROBIOLOGY Study Guide - Type Iii Hypersensitivity, Type Iv Hypersensitivity, Autoimmune Disease
4 Jan 2022
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Document Summary
Involves the overproduction of immune complexes (figure 33. 23). Normally these complexes are phagocytosed effectively by dendritic cells and macrophages. But when an excessive number of igg or igm antibody-antigen complexes are formed, they may not be efficiently removed. Their accumulation can lead to a hypersensitivity reaction by stimulating complement that triggers a variety of inflammatory processes. Type iv hypersensitivity involves delayed, cell-mediated immune reactions. Therefore, unlike types i, ii, and iii hypersensitivities, type iv is mediated by. Both th and ctl cells can elicit type iv hypersensitivity reactions, depending on the pathway in which the antigen is processed and presented. Autoimmunity and autoimmune diseases the importance of the immune system s ability to distinguish between self and non-self-antigens is dramatically illustrated by autoimmune diseases. In these conditions, the body loses tolerance and mounts an abnormal immune attack, either with antibodies or t cells, against its own self antigens. It is important to distinguish between autoimmunity and autoimmune disease.
