Cells from the body’s immune system can on occasion react against normal endogenous proteins and thereby effect a reaction against certain body tissues. This ab-normal immune response is termed autoimmunity. Ordinarily, a complex network of feedback loops keeps autoimmune reactions in check. However, under certain circumstances, normal control is lost and the aberrant immune reaction will result in disease.
Myasthenia gravis is an example of an autoimmune disease in which antibodies are produced against the acetylcholine receptors in the neuromuscular junction. The abnormal immune response results in the break-down of junctional receptors, ultimately rendering pa-tients weak and unable to move voluntary muscles. Rheumatoid arthritis is another autoimmune disease in which antibodies are secreted against a component of an individual’s own immune globulins. These antibody–immune globulin conjugates (immune com-plexes) form precipitates in the joints of affected indi-viduals. Phagocytic cells are in turn attracted to these sites, where they release enzymes that destroy sur-rounding tissue (inflammation). Immunosuppressive agents are often employed in debilitating cases of au-toimmune disease to curb the production of autoanti-bodies.
A list of autoimmune diseases for which immuno-suppressive therapy is commonly used can be found in Table 57.1.
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