Relationship between lymphocyte cyclosporin sensitivity and clinical progress of psoriasis

Cyclosporin (CYA) is a therapeutic agent used in the treatment of psoriasis vulgaris. However, the effectiveness of CYA therapy varies among patients. In the present study, due to the fact that CYA mainly acts on lymphocytes, we hypothesized that a measurement of the sensitivity of lymphocytes to CYA in vitro (IC50) could be applied to patients with psoriasis vulgaris to determine therapeutic success. We measured IC50 levels of 32 patients presenting with psoriasis prior to CYA administration, and classified them into three groups according to IC50 levels: favorable, moderate and low sensitivity. CYA sensitivity levels were correlated with the degree of improvements in psoriasis area and severity index (PASI) scores, CYA dosage and occurrence of side-effects (hepatopathy and nephropathy). Results showed the degree of improvement in PASI scores differed significantly between the favorable and low sensitivity groups (P < 0.05). Furthermore, CYA dosage was lowest in the favorable sensitivity group and highest in the low sensitivity group. Moreover, hepatopathies and nephropathies were detected in the low and moderate sensitivity groups, but not in the favorable sensitivity group. These results suggest that the effectiveness of CYA therapy as a treatment of psoriasis vulgaris is affected by the sensitivity of lymphocytes in each patient.