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Autoimmune Disease

The immune system is the body's defense against foreign substances, such as bacteria or viruses, that may be harmful. An autoimmune disease is an abnormal condition that occurs when a person's immune system attacks its own tissues as though they were foreign substances.

  • Normally, when a foreign substance enters the body, the immune system creates special cells to attack and destroy the foreign substance. These cells include antibodies and white blood cells (lymphocytes).
  • In a person with an autoimmune disease, the immune system recognizes some of the person's own tissues as foreign substances. The body makes antibodies and other cells that attack and destroy these tissues. This process often leads to inflammation and eventually, if it continues, scarring and destruction of the organs that are made up of those tissues.

Why the body attacks its own cells is not known. Autoimmune diseases include lupus, rheumatoid arthritis, scleroderma, and Sjögren's syndrome. Certain types of diabetes and thyroid disease are related to autoimmune reactions. People who have autoimmune diseases are at an increased risk for infections.

By Healthwise Staff
Primary Medical Reviewer Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer Nancy Ann Shadick, MD, MPH - Internal Medicine, Rheumatology
Current as of May 10, 2012

WebMD Medical Reference from Healthwise

Last Updated: May 10, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.