Sulfasalazine therapy in psoriatic arthritis: clinical and immunologic response.

Sulfasalazine therapy has been shown effective in rheumatoid arthritis and ankylosing spondylitis. We treated 10 patients with active polyarticular psoriatic arthritis with 2 g/day of sulfasalazine for 16 weeks. Significant improvement was seen in joint count score, morning stiffness, and patient/physician assessment of disease activity. Toxicity requiring drug cessation was seen in only 1 patient. Patients with psoriatic arthritis had elevated B cells and immunoglobulin levels which fell with sulfasalazine therapy. Minimal changes were seen in T cell subsets. Sulfasalazine appears to be an effective second line agent for the treatment of psoriatic arthritis. Its mechanism of action may in part relate to alteration of B cell number and function.