Since the discovery (Tan and Kunkel, 1966; Mattioli and Peichlin, 1971; Sharp, et al., 1972) of human SLE autoantibodies directed against RNA-protein complexes in eucaryotic nuclei, a great deal of interest has been generated regarding both the relationships of antibody specificities to disease and the biological roles of the recognized antigens. These antibodies are some of the many autoantibody species which have been described in systemic lupus erythematosus (SLE) as well as other rheimatic disease conditions. A common feature of many of these reactivities is the apparent nuclear localization of antigen. Study of the antibodies as well as these antigens has led to formation of a particularly unique bridge between clinical medicine and basic science questions in cellular biology and metabolism. The spectrum of diseases which present with antibodies directed against cellular constituents is vast although certain features of these conditions imply common aspects which may, furthermore, be of some diagnostic use
