Impaired antigen-specific suppressor cell activity in psoriasis and psoriatic arthritis.

Antigen specific suppressor cell activity of peripheral blood mononuclear cells was investigated in 20 patients with psoriatic arthritis and 18 patients with uncomplicated psoriasis and compared to that of 27 age- and sex-matched healthy controls and 18 patients with osteoarthritis. Topical skin therapy and nonsteroidal anti-inflammatory medications were allowed but patients who had taken disease suppressive, immunosuppressive, cytotoxic, and systemic steroid therapy were excluded. The results demonstrate reduced suppressor cell activity (SCA) in patients with psoriatic arthritis compared to normal controls (54.8% +/- 4.9 vs 68.4 +/- 2.8, p less than 0.005). Similarly, the response of patients with uncomplicated psoriasis was significantly lower than normal (50.1 +/- 4.9 vs 67.3 +/- 3.0% p less than 0.005). Five of the 20 patients with psoriatic arthritis and 7 of the 18 patients with uncomplicated psoriasis demonstrated SCA of more than 2 SD below the normal mean. The SCA of patients with osteoarthritis was normal. The plaque forming cell (PFC) response of patients with psoriatic arthritis and uncomplicated psoriasis was not different from those of the normal controls or of patients with osteoarthritis. There was no correlation between impaired suppression and disease activity or therapy.