Objective: To determine the clinical significance of anti-Ro antibodies in patients with rheumatoid arthritis (RA).
Methods: Cross sectional study of 278 consecutive patients with RA at a single academic rheumatology center. Clinical data were collected without knowledge of the anti-Ro status. Anti-Ro antibodies were detected in coded sera using immunoprecipitation of HeLa cell extracts.
Results: Ten (3.6%) of the 278 patient sera were found anti-Ro positive. Age, sex, duration of disease, prevalence of rheumatoid factor (RF), and severity of joint involvement were similar in anti-Ro positive and negative patients. Anti-Ro positive patients had significantly more symptomatic Sjögren's syndrome (SS), leukopenia, hypocomplementemia, vasculitic purpura, and photosensitivity (odds ratio [OR] varying from 7.3 to 26.8). Although SS was frequent in anti-Ro positive patients with RA, secondary SS was not independently linked to any of the associated extraarticular manifestations. Histocompatibility studies revealed the absence of HLA-DR4 in the 8 anti-Ro positive patients available for typing and the presence of DR2 and/or DR3 in 6 of them.
Conclusions: Immunoprecipitating anti-Ro antibodies in serum delineate a clinical, non-HLA-DR4 associated cluster of patients with RA almost as numerous as systemic lupus erythematosus or primary SS. Production of these antibodies seems to precede clinical manifestations and may thus have prognostic implications.