1. I. Viard, P. Wehrli, R. Bullani, D. Salomon, J.-H. Saurat, L. E. French, Department of Dermatology, Geneva University Medical School, CH-1211 Geneva 4, Switzerland. P. Schneider, N. Holler, J. Tschopp, Institute of Biochemistry, University of Lausanne, BIL Research Center, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland. T. Hunziker, Department of Dermatology, University of Bern, Medical School, CH-3010 Bern, Switzerland.