Reticuloendothelial system Fc receptor function in rheumatoid arthritis

Patients with systemic lupus erythematosus (SLE) have abnormal reticuloendothelial system (RES) IgG Fc receptor function which is correlated with disease activity and levels of immune complexes (IC). We studied RES function, IC levels, clinical and laboratory manifestations in 43 patients with RA. The articular index was abnormal in 42 patients (range of 6 to 153). Thirty were seropositive; 31 had an elevated erythrocyte sedimentation rate. Extraarticular manifestations included nodules (25), anemia (19), Sjogren's syndrome (6), vasculitis (4), and Felty's syndrome (2). Medication included corticosteroids (32), nonsteroidal antiinflammatory drugs (33), slow acting antirheumatic drugs (18), and cytotoxics (2). Thirty-three patients had IC (30 by the Clq binding assay, 21 by the Raji cell assay); 13 patients had normal RES function (t( 1/2 )-24-60 min; upper 95% confidence limit in normals = 62 min). Thirty had prolonged clearance times (65-210 min, mean 106 min). In contrast to SLE, clearance times were not found to be correlated with IC levels, or clinical or laboratory measures of disease activity. Defective RES immune clearance may not be an important determinant in the pathogenesis of immunologic tissue damage in rheumatoid arthritis.