ANTINUCLEAR ANTIBODIES - A group of antibodies that react against components of the cell nucleus. These antibodies are present in a variety of immunologic diseases including lupus, scleroderma, Sjogren's syndrome, rheumatoid arthritis, polymyositis, dermatomyositis, and in persons taking hydralazine, procainamide, or isoniazid. A serologic measurement for antinuclear antibodies can aid in the diagnosis of unexplained arthritis, rashes, or chest pains.