Rheumatoid arthritis (RA) is a common form of arthritis that affects more than two million Americans and six million people worldwide. RA usually involves inflammation of small joints and cartilage destruction. Patients typically suffer from pain, swelling, stiffness, and loss of motion in the joints. RA eventually may lead to disability and decreased life expectancy.

RA is a disease of the immune system -- the body’s protection against invasion of infections and toxins. In these diseases, the immune system attacks the body’s own healthy cells, mistaking them for cells that do not belong. This causes inflammation of the lining or connective tissue of the joints, or other parts of the body.

Tumor necrosis factor (TNF) is one of the chemical messengers that helps regulate the inflammatory process. When the body produces too much TNF, it overwhelms the immune system’s ability to control inflammation in the joints.

Though joint erosion can begin early in RA, more than half the people with this debilitating disease are undiagnosed or not seeking treatment. If left untreated, RA patients can become disabled from progressive joint damage, limiting their ability to function.