What are autoimmune disorders?
Autoimmune disorders are diseases that occur when the body produces an inappropriate immune response against its own tissues. Sometimes the immune system will cease to recognize one or more of the body's normal constituents as "self" and will produce autoantibodies – antibodies that attack its own cells, tissues, and/or organs. This causes inflammation and damage and leads to autoimmune disorders.
The cause of autoimmune diseases is unknown, but it appears that there is an inherited predisposition in many cases. In a few types of autoimmune disease (such as rheumatic fever), a virus or infection with bacteria triggers an immune response and the antibodies or T-cells attack normal cells because some part of their structure resembles a part of the infecting microorganism.
Autoimmune disorders fall into two general types: those that damage many organs (systemic autoimmune diseases) and those where only a single organ or tissue is directly damaged by the autoimmune process (localized). However, the distinctions become blurred as the effect of localized autoimmune disorders frequently extends beyond the targeted tissues, indirectly affecting other body organs and systems.
In some cases, the antibodies may not be directed at a specific tissue or organ; for example, antiphospholipid antibodies can react with substances (phospholipids) that are the normal constituents of platelets and the outermost layer of cells (cell membranes), which can lead to the formation of blood clots within the blood vessels (thrombosis).
Symptoms of autoimmune disorders vary by the particular disorder but many include fatigue, dizziness, and low grade fever. Symptoms can also vary in severity over time.
Laboratory tests performed to diagnose autoimmune disorders depend on the particular disorder the doctor suspects a person has, but usually include autoantibody tests as well as tests for inflammation such as CRP and ESR.
Some examples of autoimmune disorders are listed on the next page.