Autoimmune diseases are complicated and often dangerous illnesses that affect the endocrine system, which produces the body's cell-regulating hormones. More than 60 different illnesses are considered autoimmune diseases, because each one causes the immune system to turn against different parts of the body. In each case, the body sends signals through the hormones to produce anti-antibodies that attack the person's own tissue. Examples include rheumatoid arthritis, lupus, multiple sclerosis, juvenile diabetes, myasthenia gravis, Grave's disease, scleroderma, and chronic vasculitis.

A clear cause of these diseases has not been found. Some diseases may be caused by heredity, in which one parent may have rheumatoid arthritis, the child may have lupus and a cousin has multiple sclerosis. Others may be caused by a virus or bacteria that irreversibly alters the immune system. Or, it may be a combination of both when someone with a genetic predisposition to an autoimmune...