Delayed-type hypersensitivity in palmoplantar pustulosis: effect of cyclosporin A treatment on skin testing with recall antigens.

Delayed-type hypersensitivity reactions to skin antigens are an indirect measure of cellular immune response. We studied in a double-blind manner whether clinically effective doses of cyclosporin A in palmoplantar pustulosis would diminish delayed-type hypersensitivity reactions in vivo. For testing delayed-type hypersensitivity, we applied intradermally a standardized panel of seven recall antigens and a vehicle control in 30 patients with palmoplantar pustulosis, and 28 were tested both at baseline and after 4 weeks. For 4 weeks 14 patients were treated with 2.5 mg/kg/day cyclosporin A and 14 patients with placebo. Cyclosporin A but not placebo caused a significant decrease in clinical disease parameters. In contrast, no significant differences in delayed-type hypersensitivity reactions between treatment groups were observed. The results do not support the view that the efficacy of low-dose cyclosporin A in dermatological disorders can be entirely explained by cyclosporin A's inhibitory actions on effector T-cells.