Inflammation is a normal part of the immune system’s effort to protect the body. It begins when white blood cells are attracted to the site of an infected area. As they attempt to destroy bacteria or other harmful foreign organisms, they produce a cellular reaction that triggers inflammation. Inflammation therefore indicates that your immune system is working.

In rheumatoid arthritis (RA), however, this natural immune response goes awry and, for unknown reasons, begins attacking healthy tissues. At the beginning stages of RA, white blood cells move to your joints, releasing products that inflame the synovial membrane and cause fluid to accumulate within the joint cavity. The joint becomes red, warm, swollen and painful. In most people, the disease does not progress further.

In severe cases, an invasive mass of tissue (called a pannus) begins to grow on the surface of the cartilage. The pannus produces enzymes that eat away at the cartilage and bone within the joint. Without treatment, joint instability and deformity can result.

In many people with RA, lifestyle measures can help ease symptoms, and proper drug treatment can control symptoms and slow disease progression.