Intralesional cyclosporin in psoriasis: effects on T lymphocyte and dendritic cell subpopulations

On each of 10 patients with untreated plaque psoriasis, two symmetrical plaques were injected with cyclosporin A or placebo on six occasions over 12 days, in a double-blind manner. Biopsies taken from these lesions at 14 days were examined for differences in cellular composition using a double-labelling immunofluorescent technique. The cyclosporin-injected plaques cleared significantly better than those injected with placebo (P less than 0.001). In the epidermis of the cyclosporin-injected plaques, total and HLA-DR+ CD4+ and CD8+ T cell numbers were significantly decreased compared to corresponding plaques treated with placebo (total CD4+, total CD8+, DR+ CD4+, P less than 0.01; DR+ CD8+, P less than 0.02). Similarly, T lymphocyte numbers in the dermis were decreased in the cyclosporin compared to placebo-treated plaques; the reduction in total CD4+ and DR+ CD8+ T cell numbers was statistically significant (P less than 0.05). Although total numbers of epidermal dendritic cells were not significantly altered, the DR+CD1- dendritic cell subpopulation was markedly decreased (P less than 0.01) and DR-CD1+ dendritic cells increased (P less than 0.05) in the plaques injected with cyclosporin compared to corresponding placebo-treated plaques. These findings show that cyclosporin injected in situ is effective in clearing psoriasis and probably exerts this beneficial effect by its action on T lymphocytes. A suitable topical preparation that allows penetration of the drug should prove helpful in the treatment of psoriasis.