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

Objective. To study local cellular immune reactions in the pleural fluid of patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Methods. 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