Autoimmune illnesses are characterized by a loss of self-tolerance, whereby the body's own immune defense mechanisms are inappropriately directed against body components, resulting in organ damage or activation of a systemic immune response. Some organ-specific autoimmune illnesses are self-limited, since only one tissue is affected, but the ongoing inflammatory response may interfere with normal organ function. However, multisystem autoimmune illnesses, such as rheumatoid arthritis (characterized by chronic inflammation of the synovium, or the lining membrane, of joints, and surrounding tissue, as well as other body systems) have the propensity to involve multiple organs. If the immune response is not adequately suppressed during times of increased disease activity, then organ failure, death, or permanent disability may result.