• Home

Home > Medical Reference > Encyclopedia (English)

Toggle: English / Spanish

Autoimmune disorders

• Overview
• Symptoms
• Treatment
• Prevention

Definition:

An autoimmune disorder is a condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue. There are more than 80 different types of autoimmune disorders.

See also: Immune response

Causes, incidence, and risk factors:

Normally the immune system's army of white blood cells helps protect the body from harmful substances, called antigens. Examples of antigens include bacteria, viruses, toxins , cancer cells, and foreign blood or tissues from another person or species. The immune system produces antibodies that destroy these harmful substances.

But in patients with an autoimmune disorder, the immune system can't tell the difference between healthy body tissue and antigens. The result is an immune response that destroys normal body tissues. The response is a hypersensitivity reaction similar to allergies , where the immune system reacts to a substance that it normally would ignore. In allergies, the immune system reacts to an external substance that would normally be harmless. With autoimmune disorders, the immune system reacts to normal body tissues.

What causes the immune system to no longer distinguish between healthy body tissues and antigens is unknown. One theory holds that various microorganisms and drugs may trigger some of these changes, particularly in persons who are genetically prone to autoimmune disorders.

An autoimmune disorder may result in:

• The destruction of one or more types of body tissue
• Abnormal growth of an organ
• Changes in organ function

An autoimmune disorder may affect one or more organ or tissue types. Organs and tissues commonly affected by autoimmune disorders include:

• Red blood cells
• Blood vessels
• Connective tissues
• Endocrine glands such as the thyroid or pancreas
• Muscles
• Joints
• Skin

A person may have more than one autoimmune disorder at the same time. Examples of autoimmune (or autoimmune-related) disorders include:

• Hashimoto's thyroiditis
• Pernicious anemia
• Addison's disease
• Type I diabetes
• Rheumatoid arthritis
• Systemic lupus erythematosus
• Dermatomyositis
• Sjogren syndrome
• Lupus erythematosus
• Multiple sclerosis
• Myasthenia gravis
• Reactive arthritis
• Grave's disease
• Celiac disease - sprue

• Review Date: 5/27/2007
• Reviewed By: Steve Lee, DO, Rheumatology Fellow, Loma Linda University Medical Center, Loma Linda, CA. Review provided by VeriMed Healthcare Network.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process . A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 1997-2007 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.