1. Department of Pathology and Medical Biology University Medical Centre Groningen Groningen The Netherlands
2. Department of Dermatology University Medical Centre Groningen Groningen The Netherlands
3. Ludwig Boltzmann Institute for Hematology and Oncology Medical University of Vienna Vienna Austria
4. Department of Internal Medicine I, Division of Hematology and Hemostaseology Medical University of Vienna Vienna Austria
5. Institute for Pathology Ludwig‐Maximilians University Munich Germany
6. Department of Allergy and Immunology University Medical Centre Groningen Groningen The Netherlands