1. From the Department of Medicine I, Bone Marrow Transplantation Unit, University of Vienna, Vienna, Austria; Department of Dermatology, Division of Immunology, Allergy and Infectious Diseases, University of Vienna, Vienna, Austria; Department of Blood Group Serology, University of Vienna, Vienna, Austria; Department of Dermatology, Division of Special and Environmental Dermatology, University of Vienna, Vienna, Austria.