Synovial fluid findings in systemic lupus erythematosus (SLE)

Synovial fluids from 26 patients with SLE were usually clear and viscous, with few WBCs and low complement. Twelve fluids, studied in detail, were further characterized according to protein and IgG concentrations. Four were transudates. Fluids from 3 subjects with atypical features of SLE were exudates that contained increased concentrations of proteins and complement. Five other fluids were exudates with very low complement, thus similar to rheumatoid effusions, but lacking the polymorphonuclear leukocytosis and rheumatoid factor found in RA.