1. From the Haemostasis Research Unit, Max-Planck Institute, Kerckhoff-Klinik, D-61231 Bad Nauheim, Germany; the Finsen Laboratory, Rigshospitalet, DK-2100 Copenhagen, Denmark; the Basel Institute for Immunology, CH-4001 Basel, Switzerland; and the Department of Pathology, Centre Medical Universitaire, CH-1211 Geneva 4, Switzerland