Pleural fluid soluble interleukin 2 receptor in rheumatoid arthritis and systemic lupus erythematosus.

Abstract

To study local cellular immune reactions in the pleural fluid of patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Using an immunoenzymometric assay, the concentration of soluble interleukin 2 receptor (sIL-2R) was measured in the pleural fluid of 13 patients with RA, 6 patients with SLE and 72 patients with pleural effusions of other etiologies, including tuberculosis, cancer, pneumonia and congestive heart failure. The mean pleural fluid sIL-2R concentration was significantly higher in patients with RA (593 pM, range 252-1558) than in patients with SLE (145 pM, range 94-236; p < 0.005), cancer (224 pM, range 98-521, p < 0.01), pneumonia (177 pM, range 60-343, p < 0.005) and congestive heart failure (139 pM, range 56-228, p < 0.005), but as high in patients with tuberculous pleurisy (mean 390 pM, range 151-512). The highest mean pleural fluid to serum sIL-2R ratios were observed in patients with RA and with tuberculosis. Measurement of sIL-2R in pleural fluid is useful for the differentiation of pleural effusions in RA from those occurring in SLE. High levels of sIL-2R associated with a local T cell mediated immune reaction may serve an immunoregulatory purpose in rheumatoid pleurisy.