What are autoimmune diseases?


One of the functions of the immune system is to protect the body by responding to invading microorganisms, such as viruses or bacteria, by producing antibodies or sensitized lymphocytes (types of white blood cells). Under normal conditions, an immune response cannot be triggered against the cells of one’s own body. In some cases, however, immune cells make a mistake and attack the very cells that they are meant to protect. This can lead to a variety of dysimmune or autoimmune diseases. They encompass a broad category of related diseases in which the person’s immune system attacks his or her own tissue. These diseases can affect any part of the body, weakening bodily function and even becoming life-threatening.

Scientists know about more than 80 autoimmune diseases. Some are well known, such as type 1 diabetes, multiple sclerosis, lupus, and rheumatoid arthritis, while others are rare and difficult to diagnose. With unusual autoimmune diseases, patients may suffer years before getting a proper diagnosis. Most of these diseases have no known cure. Some require lifelong treatment to ease symptoms. Treatment for autoimmune diseases generally focuses on reducing or mediating immune system activity.

Collectively, these diseases affect more than 24 million people in the United States (NIH Autoimmune Diseases Coordinating Committee: Progress in Autoimmune Diseases Research, March 2005.) An additional eight million people have auto-antibodies, blood molecules that indicate a person’s chance of developing autoimmune disease. Autoimmune diseases are more frequent in women than in men, and the presence of one autoimmune disease increases the chance for developing another simultaneous autoimmune disease.