Abnormal T-cell function in patients with psoriatic arthritis: evidence for decreased interleukin 2 production.

Psoriatic arthritis (PSA) is an inflammatory arthritis associated with psoriasis. Although not considered an autoimmune process, there is evidence for humoral and cellular immune abnormalities similar to autoimmune diseases such as rheumatoid arthritis and systemic lupus (SLE). We investigated mitogen-induced proliferation and interleukin 2 (IL-2) production by peripheral blood mononuclear cells in patients with PSA. Both IL-2 production and proliferation were significantly decreased in PSA patients when compared to controls. Increased arachidonic acid metabolism has been reported in skin and peripheral mononuclear cells of patients with psoriasis and PSA. We therefore also investigated the effect of indomethacin and prostaglandin E2 (PGE2) on IL-2 production. Addition of indomethacin to cultures did not significantly change IL-2 production in patients with PSA, but did so in controls. PGE2 produced a significant reduction in IL-2 production in PSA and in controls.