ANALYSIS OF AUTOANTIBODIES AGAINST RNA-POLYMERASES USING IMMUNOAFFINITY-PURIFED RNA-POLYMERASE-I, RNA-POLYMERASE-II, AND RNA-POLYMERASE-IIIANTIGEN IN AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY

Autoantibodies against RNA polymerases (RNAP) have been reported to oc cur in patients with a wide variety of connective tissue diseases (CTD ), including systemic sclerosis (SSc), systemic lupus erythematosus (S LE), and mixed connective tissue disease (MCTD). The frequency of anti -RNAP antibodies has been reported to vary widely between different CT D diseases in studies examining different patient populations. Further more, these studies have been limited by the fact that methods have no t previously been available for detecting antibodies against RNAP whic h are both rapid and quantitative. We have developed an enzyme-linked immunosorbent assay (ELISA) for rapidly quantitating antibodies agains t RNAP I, II, and III. We have utilized both the ELISA and the immunop recipitation of S-35-labeled HeLa cells to analyze sera from a large c ohort of well-characterized Caucasian CTD patients for the presence of anti-RNAP antibodies. We found excellent concordance for the presence of anti-RNAP antibodies using immunoprecipitation and ELISA. Anti-RNA P antibodies occurred predominantly among female patients with the dif fuse form of SSc and were detected in 8/36 (22%) of Caucasian patients with diffuse SSc and 1/53 (2%) with limited SSc. Anti-RNAP antibodies occurred in 1/42 (2%) of patients with SLE. Anti-RNAP antibodies did not occur in MCTD (0/49). Antibodies against RNAP were rare among anti nucleolar-reactive sera, occurring in only 3/200 (1.5%). The RNAP ELIS A provides a validated method which can be rapidly utilized in a clini cal diagnostic laboratory setting to identify SSc patients who are at risk. for developing diffuse SSc with multiorgan involvement and hyper tensive renal crisis. (C) 1998 Academic Press.