A STUDY OF THE EFFECT OF RHEUMATOID SYNOVIAL-FLUID ON PROLIFERATION AND IL-2 PRODUCTION BY TOTAL MONONUCLEAR-CELLS AND PURIFIED CD4+ CELLS OF SYNOVIAL-FLUID AND PERIPHERAL-BLOOD

T cells from synovial fluid (SF) of rheumatoid arthritis (RA) patients have previously been shown to proliferate less after mitogenic stimulation and produce less interleukin 2 (IL-2) than normal T cells. To test whether SF is responsible for the reduced T-cell responses, we studied the effect of inflammatory SF on peripheral blood (PB) RA and normal mononuclear cells (MNC) and CD4+ T cells and on RA SF MNC and CD4+ cells in vitro. Most rheumatoid SF present in concentrations of 50% and 5% during in vitro stimulation increased mitogen-induced IL-2 production and proliferative response by normal PB and RA MNC and CD4+ cells. Other rheumatoid SF samples did not influence the T cell responses, while only a few samples had an inhibitory effect. The results indicate that SF contain both stimulatory and inhibitory factors and that the resultant effect on T cells may depend on the net effect of these. The results do not support the hypothesis that the apparently impaired function of SF T cells is due to contact with SF.