EROSIVE ARTHRITIS IN SYSTEMIC LUPUS-ERYTHEMATOSUS - ANALYSIS OF A DISTINCT CLINICAL AND SEROLOGICAL SUBSET

Erosive arthritis (EA) in systemic lupus erythematosus (SLE) call be d ebilitating and deforming with uncertain factors for risk, although an tibodies to the A2 hnRNP core protein, known as anti-RA33, have been a ssociated with EA. Two hundred patients under long-term follow-up for SLE were evaluated for EA and associated clinical and serological abno rmalities. In addition, sera were tested in a masked fashion for anti- RA33 antibodies in a total of 60 patients: 10 with EA and 50 age-, sex - and ethnically matched controls. Ten of 200 (5%) patients with SLE, mainly non-white women, had EA. There were trends For increased renal involvement (P = 0.06), Sjogren's syndrome (P = 0.07) and Raynaud's ph enomenon (P = 0.03) in patients with EA compared to those without EA. Rheumatoid factor (RF) was increased in patients with EA (P < 0.02), a s were antibodies to double-stranded DNA (P < 0.05), Sm (P < 0.01) and La/SS-B (P < 0.001). Anti-RA33 antibodies were present in 70% with EA compared to 28% without EA (P < 0.05). RF correlated with anti-RA33 a ntibodies in patients with EA, but not with the presence of anti-RA33 alone. Thus, anti-RA33 antibodies may identify those patients with SLE who are at risk for EA, and an association with RF suggests a common immune response or pathological mechanism in autoimmune erosive joint disease.