Systemic Autoimmunities

Examples of Autoimmune Disease

One of the most severe chronic autoimmune diseases is systemic lupus erythematosus (SLE) or lupus. This name originated fromthe characteristic butterfly-shaped rash that drapes across the noseand cheeks. Apparently, ancient physicians thoughtthe rash resembled a wolf bite (lupus is Latin for “wolf”). Althoughthe manifestations of the disease vary considerably, all patients produceautoantibodies against a great variety of organs and tissues.The organs most involved are the kidneys, bone marrow, skin, nervoussystem, joints, muscles, heart, and GI tract. Antibodies to intracellularmaterials such as the nucleoprotein of the nucleus andmitochondria are also common.

In SLE, autoantibody-autoantigen complexes appear to be deposited in the basement membranes of various organs. Kidney failure, blood abnormalities, lung inflammation, myocarditis, and skin lesions are the predominant symptoms. One form of chronic lupus (called discoid) is influenced by exposure to the sun and primarily afflicts the skin. The etiology of lupus is still a puzzle. It is not known how such a generalized loss of self-tolerance arises, though viral infection or loss of T-cell suppressor function is suspected.

The fact that women of childbearing years account for 90% of cases indicates that hormones may be involved. The diagnosis of SLE can usually be made with blood tests. Antibodies against the nucleus and various tissues (detected by indirect fluorescent antibody or radioimmune assay techniques) are common, and a positive test for the lupus factor (an antinuclear factor) is also very indicative of the disease.

Rheumatoid arthritis, another systemic autoimmune disease, incurs progressive, debilitating damage to the joints. In some patients, the lung, eye, skin, and nervous systems are also involved. In the joint form of the disease, autoantibodies form immune complexes that bind to the synovial membrane of the joints and activate phagocytes and stimulate release of cytokines. Chronic inflammation leads to scar tissue and joint destruction. The joints in the hands and feet are affected first, followed by the knee and hip joints.The precipitating cause in rheumatoid arthritis is not known, though infectious agents such as Epstein-Barr virus have been suspected. The most common feature of the disease is the presence of an IgM antibody, called rheumatoid factor (RF), directed against other antibodies. This does not cause the disease but is used mainly in diagnosis.

Дата добавления: 2015-06-04