Scl-70 antibody

Belong to the group of antibodies against "extractable nuclear antigens"(ENA). Scl-70 autoantibodies are directed against DNA topoisomerase I, a 100kD protein which is nucleoplasmically and nucleolarily localized. In indirect immunofluorescence, Scl-70 autoantibodies show a mostly diffuse granular distribution of the antigen in the cell nucleus. Scl-70 antibodies are detected in systemic lupus erythematosus (SLE) in 25-75% of cases.

They are also indicative of diffuse scleroderma (frequency up to 70%). As a rule, this autoantibody correlates with a more severe course and unfavourable prognosis. In patients with limited scleroderma, SCl-70-Ak is only detected in about 20% of cases. Furthermore, Scl-70 antibodies are found in overlap syndromes with other collagenoses.