The relationship between serum-soluble interleukin-2 receptor and radiological evolution in psoriatic arthritis patients treated with cyclosporin-A

Aims of the study to evaluate the radiologically detected progression of joint damage in patients with psoriatic arthritis (PA) treated with cyclosporin-A (CsA) and to look for clinical and/or immunological parameters that might predict outcome. Twenty-four out-patients suffering from active PA entered a 2-year open prospective study on low-dose CsA (starting dose 3 mg/kg/day). Fifteen patients completed the study. Plain radiographs of hands and feet at study entry and at the end of follow-up were compared for the number of eroded joints. Serum-soluble IL-2 receptor (sIL-2R) levels were available in 13/15 patients before CsA therapy, after 6 months and after 2 years. The mean number of eroded joints per patient increased significantly during the study period (P = 0.017). Nine patients had less than two new eroded joints (responders) while the remaining six patients had five or more new eroded joints (non-responders). Serum sIL-2R levels were in the normal range after 6 months and 2 years of CsA treatment in all the responder patients and were above the 95th percentile of the control population in the six non-responders. We did not find any other demographical, clinical, radiological or laboratory parameter predictive of outcome in conclusion. (1) CsA seems to be able to control the 2-year progression of the radiologically measured damage in peripheral joints in 60% of PA patients. (2) A normal serum sIL-2R level after 6 months of therapy seems to have a prognostic value for a good outcome in PA patients treated with CsA.