AUTOANTIBODIES IN SCLERODERMA AND RAYNAUD'S PHENOMENON

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Anticentromere antibodies (ACA) present in sera from patients with CREST or Raynaud's phenomenon with or without a connective tissue disease or in Raynaud's disease have been found to react with 3 centromeric proteins (CENPs): CENP-A, CENP-B and CENP-C. CENP-B which appears to be the major autoantigen has been cloned and is expressed in E. coli. Anti-Scl-70 has been shown to react with topoisomerase I which has also been cloned. Using immunoblotting technique, anti-toposomerase I can be demonstrated in sera negative for anti-SCL-70 on immunodiffusion. Preliminary data suggests that the presence of anti-topoisomerase I may predict the development of scleroderma and that anti-CENP-B may predict the development of CREST syndrome. The presence of antibodies to the 3 centromeric proteins and topoisomerase I will be studied by immunoblotting with chromosomes. The level of anti-CENP-B and topoisomerase I will be studied by ELISA assay using the fusion protein CENP-B and topoisomerase I. We postulate that there is a common genetic background in patients with these autoantibodies which can be demonstrated by looking for the presence of cross reactive idiotypes. Affinity purified auto-antibodies to CENP-B and to topoisomerase I and autoantibodies to CENP-B and topoisomerase I generated by human-human hybridomas will be used to produce polyclonal anti-idiotypes in rabbits and monoclonal anti-idiotypes in mice. We will look for cross reactive idiotypes in sera from patients and their relatives. Sera containing cross reactive idiotype will be studied using electrofocusing and labelled antigen to determine whether or not the cross reactive idiotype reacts with antigen. A prospective study of patients with Raynaud's phenomenon unassociated at the onset with a connective tissue disease will be carried out to determine the clinical significance of the presence and amount of anti-CENP-B and topoisomerase I. In addition, the prognostic significance of the presence of anti-CENP-A and anti-CENP-C will be determined.