Cytokines and the chronic inflammation of rheumatic disease. III. Deficient interleukin-2 production in rheumatoid arthritis is not due to suppressor mechanisms.

Despite the evidence for activated T cells in the joint in rheumatoid arthritis (RA), there is evidence of deficient lymphocyte proliferation to a variety of stimulants. We investigated the production of interleukin-2 (IL-2) after phytohemagglutinin (PHA) stimulation. We show that in the peripheral blood IL-2 production was similar in RA and controls (3.7 vs 3.0 U/ml, respectively). However, blood lymphocytes from patients with joint effusions produced significantly less IL-2 than from patients without effusions (1.8 vs 5.7 U/ml, respectively). The amount of IL-2 produced by synovial fluids (SF) cells was significantly less than that produced by the corresponding blood cells (1.0 vs 1.6 U/ml). Further experiments revealed that the decreased IL-2 production was not due to its removal by IL-2 receptor positive cells in the SF and cell mixing experiments did not reveal any suppressor influences.