Objective: To assess the frequency and clinical correlates of the systemic sclerosis-related autoantibodies to RNA polymerases in Italian patients.
Methods: Sera from 115 patients with systemic sclerosis (SSc) and 10 patients with systemic sclerosis-overlap syndromes recruited from a single center in northern Italy were investigated for antibodies to RNA polymerase I, II, and III by means of immunoprecipitation using 35S-labeled HeLa cell antigen extract. Twenty-five normal volunteers and 91 patients with different connective tissue diseases were studied as a control group.
Results: Antibodies to RNA-polymerases were found in 14/115 SSc patients (12.1%). None of the normal controls and none of the patients with other connective tissue diseases, including overlap syndromes, were positive. Antibodies reacting with RNA-polymerase I and III (+/- RNA-polymerase II) were found in 9/115 patients (7.8%) and were mutually exclusive with respect to other scleroderma-related autoantibodies. Isolated anti-RNA polymerase II reactivity was found in 5 patients and was associated with anti-topoisomerase I antibodies in 4 cases. Anti-RNA-polymerase I and III antibodies were associated with diffuse cutaneous involvement and male gender. Only two patients from our series had scleroderma renal crisis, and one of them had anti-RNA polymerase antibodies.
Conclusions: Anti-RNA-polymerase antibodies appear to be less frequent in Italian patients than in Caucasian patients from the United Kingdom or USA. This might be associated with the lower frequency of scleroderma renal crisis.