Objective: To determine whether the autoantibody anti-RA33, first identified in patients with rheumatoid arthritis, could define a subset of patients with lupus.
Methods: Sera from 30 patients with systemic lupus erythematosus (SLE), including serial bleeds from 8 patients were tested for anti-RA33 antibodies by immunoblotting. The results were compared to a wide range of SLE clinical features using the British Isles Lupus Assessment Group system and serological abnormalities.
Results: 12 of the 30 patients had RA33 antibodies. Their presence was associated with erosive arthropathy, and a lack of dermatological involvement in patients less likely to be Caucasian.
Conclusion: The presence of anti-RA33 antibodies appears to identify a subset of patients with SLE.