An autoimmune disorder is a malfunction of the body''s immune system that causes the body to attack its own tissues.
What triggers an autoimmune disorder is not known.
Symptoms vary depending on which disorder develops and which part of the body is affected.
Several blood tests are often used to check for an autoimmune disorder.
Treatment depends on the type of autoimmune disorder and often involves medications that suppress the activity of the immune system.
The immune system must first recognize foreign or dangerous substances before it can defend the body against them. Such substances include bacteria, viruses, parasites (such as worms), certain cancer cells, and even transplanted organs and tissues. These substances have molecules that the immune system can identify and that can stimulate a response by the immune system. These molecules are called antigens. Antigens may be contained within cells or on the surface of cells (such as bacteria or cancer cells) or be part of a virus. Some antigens, such as pollen or food molecules, exist on their own.
When certain white blood cells (B cells and T cells) encounter an antigen, they learn how to attack it and thus defend the body from the potentially dangerous antigen. B cells produce antibodies, which are one of the body''s main immune defenses against antigens. Antibodies tightly bind to a specific antigen and tag it for attack or directly neutralize it. The body produces thousands of different antibodies. Each antibody is specific to a particular antigen. Cells of the immune system remember the specific antigen so that they can attack it even more efficiently the next time they encounter it.
Cells in a person''s own tissues also have antigens. But normally, the immune system reacts only to antigens from foreign or dangerous substances, not to antigens from a person''s own tissues. However, the immune system sometimes malfunctions, interpreting the body''s own tissues as foreign and producing antibodies (called autoantibodies) or immune cells that target and attack particular cells or tissues of the body. This response is called an autoimmune reaction. It results in inflammation and tissue damage. Such effects may constitute an autoimmune disorder, but many people produce such small amounts of autoantibodies that an autoimmune disorder does not occur. Having autoantibodies in the blood does not mean that a person has an autoimmune disorder.
