ANTI-RNA POLYMERASES AND OTHER AUTOANTIBODY SPECIFICITIES IN SYSTEMIC-SCLEROSIS

Sera from 735 patients with systemic sclerosis were classified accordi ng to antinuclear antibody (ANA) pattern as follows: centromere (25%), homogeneous (26%), fine speckled (21%), fine speckled with nucleolar (14%), coarse speckled (7%), nucleolar only (3%) and cytoplasmic only (3%). Immunoprecipitations using S-35-labelled HeLa cell antigen extra ct were performed using sera from 374 of these patients to detect the systemic sclerosis-specific antibodies to RNA polymerases I and III. T he sera were selected to represent each ANA group, but focused on thos e giving fine speckled nucleoplasmic staining (with or without nucleol ar staining) where all 86 sera positive for these antibodies were conc entrated. Immunoprecipitates from a further 93 sera from patients with ANA-positive autoimmune diseases other than systemic sclerosis did no t precipitate RNA polymerases. In addition, all sera were tested for a ntibodies to the extractable nuclear antigens topoisomerase I, nRNP, R o, La and PM-Scl. Sera positive for antibodies to these antigens gave clear correlations with ANA patterns but, of the examples tested, none contained antibodies precipitating RNA polymerase I or III. Thus, ser a containing antibodies to RNA polymerases I and III were exclusive of both anticentromere and anti-topoisomerase I, and formed a major sero logical subgroup (11.7%). Clinically, 77% were patients with diffuse c utaneous disease reflected by higher skin scores and a significantly h igher incidence of renal involvement (33%) than patients with antibodi es to topoisomerase I (3%).