The exact causes of rheumatoid arthritis are unknown. Rheumatoid arthritis is most likely triggered by a combination of factors, including an abnormal autoimmune response, genetic susceptibility, and some environmental or biologic trigger, such as a viral infection or hormonal changes.
Rheumatoid arthritis is considered an autoimmune disease. In autoimmune disorders, the body’s immune system mistakenly attacks and destroys healthy cells and tissue.
The Immune Response and Inflammatory Process
The immune system is how the body responds to foreign substances (antigens) such as viruses and toxins. The immune response helps the body to fight infection and heal wounds and injuries. The inflammatory process is a byproduct of the immune response.
Two important components of the immune system that play a role in the inflammation associated with rheumatoid arthritis are B cells and T cells, both of which belong to a family of immune cells called lymphocytes. Lymphocytes are a type of white blood cell
If the T cell recognizes an antigen as "non-self," it will produce chemicals (cytokines) that cause B cells to multiply and release many immune proteins (antibodies). These antibodies circulate widely in the bloodstream, recognizing the foreign particles and triggering inflammation in order to rid the body of the invasion.
For reasons that are still not completely understood, both the T cells and the B cells become overactive in patients with RA.
Review Date: 02/16/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.