Interleukin 2 and interleukin 2 inhibitors in human serum and synovial fluid. II. Mitogenic stimulation, interleukin 2 production and interleukin 2 receptor expression in rheumatoid arthritis, psoriatic arthritis and Reiter's syndrome.

Peripheral blood and synovial fluid (SF) mononuclear cells from 30 patients with rheumatoid arthritis (RA) were hyporesponsive to mitogenic stimulation with plant lectins and CD3 antibodies, due to depressed interleukin 2 (IL-2) production and IL-2 receptor upregulation. In contrast, in the seronegative arthritis patient group only SF mononuclear cells were hyporesponsive to mitogenic stimulation and there were no significant differences in IL-2 production or IL-2 receptor upregulation as compared with control subjects. No significant correlations were observed between IL-2 inhibitor levels and mitogenic responses, IL-2 production and IL-2 receptor upregulation on peripheral blood and SF mononuclear cells but an inverse correlation was noted between SF mitogenic responses and the expression of selected activation markers. We conclude that IL-2 abnormalities appear to be most pronounced in RA compared with other inflammatory arthritides and that these changes do not appear to be directly related to serum or SF IL-2 inhibitor levels.