CD26/dipeptidyl-peptidase IV and adenosine deaminase serum levels in psoriatic patients treated with cyclosporine, etanercept, and psoralen plus ultraviolet A phototherapy

Objective The aim of this study is to determine serum levels of soluble forms of CD26/dipeptidyl‐peptidase IV (DPP‐IV) and adenosine deaminase (ADA), thought to be markers of T‐cell activation, and changes in their levels in response to cyclosporine, etanercept, and psoralen plus ultraviolet A (PUVA) treatments with respect to disease activity. Methods This study is designed as a prospective clinical study with a control group and three months of follow‐up. The study included 41 patients with psoriasis and 41 healthy controls that were older than 18 years of age. There were three different treatment groups: PUVA (n = 15), cyclosporine (n = 15), and etanercept (n = 11). To determine disease severity of patients with psoriasis, psoriasis area and severity index (PASI) scores were calculated. Results Only mean serum ADA levels were different between patients with psoriasis mean ± standard deviation (SD) = 13.9 ± 3.3 U/ml] and control group (mean ± SD = 12 ± 3.5 U/ml). Mean serum ADA levels were significantly higher before treatment than after treatment (mean ± SD = 12.4 ± 3.4 U/ml). Contrarily, following three months of therapy, mean serum CD26 levels increased significantly from 777.7 ± 214.6 to 835.3 ± 203 ng/ml (P < 0.05) and mean serum DPP‐IV activity increased significantly from 12.1 ± 4 to 15.9 ± 4.2 nmol/min (P < 0.05). There was no correlation between ADA and CD 26/DPP‐IV with PASI values. Conclusions The results show that ADA might be a useful marker indicating disease activity and T‐cell activation. As significant changes were observed in serum CD26/DPP‐IV before and after treatment, we think CD26/DPP‐IV might play a role in psoriasis pathogenesis, which should be clarified by further studies.