1 Department of Hematology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
2 Department of Laboratory Medicine, Laboratory of Hematology, Radboud University Medical Center, Nijmegen, The Netherlands.
3 Vasculitis Expertise Center Groningen, Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
4 Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.