An autoimmune disorder occurs when the body’s immune system attacks and destroys healthy body tissue by mistake. There are more than 80 types of autoimmune disorders.
The white blood cells in the body’s immune system help protect against harmful substances. Examples include bacteria, viruses, toxins, cancer cells, and blood and tissue from outside the body. These substances contain antigens. The immune system produces antibodies against these antigens that enable it to destroy these harmful substances.
When you have an autoimmune disorder, your immune system does not distinguish between healthy tissue and antigens. As a result, the body sets off a reaction that destroys normal tissues.
The exact cause of autoimmune disorders is unknown. One theory is that some microorganisms (such as bacteria or viruses) or drugs may trigger changes that confuse the immune system. This may happen more often in people who have genes that make them more prone to autoimmune disorders.
An autoimmune disorder may result in:
The destruction of body tissue
Abnormal growth of an organ
Changes in organ function
An autoimmune disorder may affect one or more organ or tissue types. Areas often affected by autoimmune disorders include:
The treatments your doctor suggests will depend on your disease and symptoms. Types of treatments include:
Supplements to replace a substance that the body lacks, such as thyroid hormone, vitamin B12, or insulin, due to the autoimmune disease
Blood transfusions if blood is affected
Physical therapy to help with movement if the bones, joints, or muscles are affected
Many people take medicines to reduce the immune system's abnormal response. These are often called immunosuppressive medicines. Examples include corticosteroids (such as prednisone) and nonsteroid drugs such as azathioprine, cyclophosphamide, mycophenolate, sirolimus, or tacrolimus.
The outcome depends on the disease. Most autoimmune diseases are chronic, but many can be controlled with treatment.
Symptoms of autoimmune disorders can come and go. When symptoms get worse, it is called a flare-up.
Complications depend on the disease. Medicines used to suppress the immune system can cause severe side effects, such as higher risk of infections.
When to Contact a Medical Professional
Call your health care provider if you develop symptoms of an autoimmune disorder.
There is no known prevention for most autoimmune disorders.
Goronzy JJ, Weyand CM. The innate and adaptive immune systems. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 44.
Kono DH, Theofilopoulos AN. Autoimmunity. In: Firestein GS, Budd RC, Gabriel SE, et al, eds. Kelley's Textbook of Rheumatology. 9th ed. Philadelphia, PA: Saunders Elsevier; 2012:chap 20.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.