Topical cyclosporin A in nickel contact hypersensitivity: results of a preliminary clinical and immunohistochemical investigation.

Four out of eighteen (22%) patients with nickel contact sensitivity showed inhibition of skin patch test responses to the allergen in the presence of topical cyclosporin A (CsA; 5% v/v). No systemic drug absorption or side effects were detected. The clinical response to CsA was accompanied by marked diminution of the T cell infiltrate, although no alteration in the helper/suppressor cell ratio was observed. Expression of the Leu 6 marker on epidermal Langerhans cells and of major histocompatibility complex (MHC) class II antigens (HLA-DR, DQ and DP) on lymphocytes and Langerhans cells was unaffected by topical CsA. The incidence of IL-2 receptor positive lymphocytes in all biopsies was too small to ascertain the influence, if any, of CsA. The prospective use and method of application of CsA in immune contact dermatitis and other immunologically-based skin disorders warrants further evaluation.