Anti-PM/Scl-100 and anti-RNA-polymerase III antibodies in scleroderma

Background: Systemic sclerosis (SSc) is a rare autoimmune disease characterized by the presence of various autoantibodies, including anti-centromere, anti-topoisomerase (Scl-70). anti-PM/Scl-100, and anti-RNA-polymerase III (RNA Pol-III) antibodies. Recently, new ELISA based immunoassays have become available for the detection of anti-PM/Scl and anti-RNA Pol-III antibodies Objective: We studied the prevalence and clinical association of anti-PM/Scl-100 (PM1-Alpha) and anti-RNA Pol-III antibodies Methods Antibodies to PM I-Alpha and RNA Pol-III were measured by ELISA (DR Fooke Laboratories and Inova Diagnostics, respectively) in 242 patients with various connective tissue diseases (CTD) (including 70 SSc patients) and in 36 non-CTD controls. Results: Low levels of PM I-Alpha antibodies were found in various CTDs, whereas high levels were exclusively found in SSc, dermatomyositis and polymyositis, albeit at low frequency (47%) Anti-RNA Pol-III antibodies were found in 7% of SSc and in 1% of non-CTD and CTD controls Anti-centromere and anti-Scl-70 antibodies were found in 37% and 21% of SSc patients, respectively. Anti-centromere antibodies were associated with limited cutaneous SSc and anti-Scl-70 antibodies with diffuse cutaneous SSc and interstitial lung disease. Because of the low number of samples positive for anti-PM/Scl-100 or RNA Pol-III antibodies, no clinical feature was statistically correlated with the presence of either reactivity, but taken together the presence of either antibody was correlated with interstitial lung disease Anti-PM1-Alpha and anti-RNA Pol-III antibodies were mutually exclusive with anti-Scl-70 antibodies. Conclusions At high levels. anti-PM/Scl-100 antibodies were associated with SSc. PM, and DM, albeit at low frequency Anti-RNA Pol-III antibodies were associated with SSc (in 7%) with high specificity (C) 2010 Elsevier B.V. All rights reserved