Autoantibodies in scleroderma

In scleroderma a profusion of circulating autoantibodies have now been defined. They include autoantibodies to Scl-70 or DNA topoisomerase 1, and to centromere/kinetochore proteins of 17.80 and 140 kilodaltons. In addition, there are several antigens which are resident primarily in the nucleolus and they are RNA polymerase 1, PM-Scl, fibrillarin and 7-2 ribonucleoprotein. Antibody to Scl-70 has been found primarily in the diffuse form of scleroderma and antibody to the centromere/kinetochore proteins in the CREST (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly and telangiectasia) subset of scleroderma. Autoantibodies to the nucleolar antigens RNA polymerase 1, PM-Scl, fibrillarin and 7-2 RNP have been detected in at least 10% of all patients with scleroderma. For several reasons which are discussed, it appears that the autoantibody response in scleroderma is antigen-driven and further that the autoantigens involved in this disease are present at some time in the nucleolus. These observations may be providing clues to some of the basic mechanisms initiating autoimmunity.