Antipruritic effect of oral cyclosporin A in atopic dermatitis

The effect of ten days' treatment with cyclosporin A, 5 mg/kg/day, in 10 adults with atopic dermatitis was investigated using a double-blind, randomized, placebo-controlled, cross-over design. Evaluation was based on itch recording, clinical scoring and immunohistochemical examination of skin biopsy specimens. Cyclosporin A significantly reduced the itch intensity, the eczema score and the consumption of topical hydrocortisone. A significant decrease in serum magnesium and in the total number of blood eosinophils was seen. No other laboratory abnormalities were observed. In lesional skin, Cyclosporin A induced a relative decrease of CD3+ T cells in 5/10 patients, of HLA-DR+ cells in 6/10, and of interleukin-2-receptor positive (CD25+) cells in 4/10. However, these changes in phenotype expression did not seem necessary for itch relief. Relapse of clinical symptoms was seen within 2-30 days of completion of the Cyclosporin A course. The mechanism of the antipruritic effect remains unclear, but the present findings may support the hypothesis that 'pruritogenic cytokines', whose production is inhibited by Cyclosporin A, may be important in the pathogenesis of itch in atopic dermatitis.