Whenever the body identi?es a substance entering it as foreign or potentially dangerous, the immune system (see IMMUNITY) produces an an antibody (see ANTIBODIES) to combat it. Antigens are normally proteins, but simple substances – for instance, metals – may become antigenic by combining with and changing the body’s own proteins. Such a product is called a hapten.... antigen
The state of having acquired an immunologic memory that says a normal cell membrane is “other”, and having forming antibody responses against it. A viral infection or organic chemical (hapten) may have started the response, but surviving healthy cells may have so close a charge pattern (epitope) that acquired immunity keeps on as if the cell was still “other”. Any physical stress that causes the target tissue to become inflamed or replicate rapidly to heal can restimulate the auto-immune response.... autoimmunity
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