If you have rheumatoid arthritis (RA), you've got plenty of company. About 1.3 million people in the U.S. have the condition; about two-thirds of them are women. RA is a chronic disease in which your immune system attacks the joints, causing pain, swelling and stiffness. This can make it harder to do things like walk, dance or just get around the house.
What is RA?
When you have RA, your immune system—which normally fights invaders—turns on itself, launching an attack on the joints. Different cells of the immune system contribute to RA in specific ways:
T cells: Normally, these white blood cells help protect the body from infection, but in people with RA, T cells become activated for no reason, worsening inflammation and jump-starting flares.
Cytokines: These immune system proteins— tumor necrosis factor-a (TNF-a), interleukin-1 (IL-1) and interleukin-6 (IL-6)—regulate the body’s inflammatory response by relaying signals to other cells of the immune system. But in RA, an oversupply of cytokines increases inflammation and triggers joint damage.
B cells: The main role of B cells is to produce antibodies that fight off germs and other foreign invaders. In RA, however, B cells go into overdrive, causing an overproduction of antibodies that contribute to RA symptoms.
What makes your joints hurt?
During an RA flare, the immune system’s T cells, B cells and cytokines take aim at the synovium—the lining of your joints. As a result, the synovium becomes swollen and inflamed and protrudes into the joint tissue, where it releases chemicals that eat away at the bone.