[Anti-Scl-70 and anti-centromere autoantibodies. Biological markers of 2 forms of systemic scleroderma]

The diagnostic and prognostic value of anti-Scl-70 autoantibodies in systemic scleroderma and other connective tissue diseases was investigated. A clinical and immunological study consisting of a search for anti-Scl-70 autoantibodies by immunodiffusion and immunoblot and a search for anti-centromere autoantibodies and antinuclear factors by indirect immunofluorescence was conducted in 57 cases of systemic scleroderma, 45 cases of CREST syndrome, 41 patients with suspected systemic scleroderma but who did not respond to the American rheumatism association (ARA) criteria, 35 cases of systemic lupus erythematosus, 8 cases of polymyositis, 40 cases of Raynaud's phenomenon and 48 controls. Anti-Scl-70 autoantibodies were found by immunodiffusion in 40 and by immunoblot in 45 cases of scleroderma with lesions proximal to the metacarpo-phalangeal joint (a major ARA criterion) and in 3 patients with suspected scleroderma but only one minor criterion: sclerodactyly. In systemic scleroderma with proximal lesions, the anti-Scl-70 autoantibody has a sensitivity of 0.85 and a specificity of 0.99. Anti-centromere autoantibodies were present in 39 cases of complete or incomplete CREST syndrome, 3 cases of Raynaud's phenomenon probably evolving towards a connective tissue disease and 1 case of systemic scleroderma with proximal lesions. The anti-Scl-70 and anti-centromere autoantibodies seem unable to coexist in the same patient and appear to be markers of two forms of scleroderma with different courses and prognoses. The Scl-70 antigen, which is the target of the anti-Scl-70 antibody, has been identified as topoisomerase 1, and a functional abnormality of this enzyme might contribute to some of the chromosomal abnormalities described in scleroderma.