1 Department of Rheumatology and Clinical Immunology, University Medical Centre Utrecht, Utrecht.
2 Department of Internal Medicine and Rheumatology, Martini Hospital, Groningen.
3 Department of Haematology, ErasmusMC, University Medical Centre Rotterdam, Rotterdam.
4 Department of Rheumatology and Clinical Immunology, University Medical Centre Groningen, Groningen, The Netherlands Correspondence to: Maarten Limper, Department of Rheumatology and Clinical Immunology, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. E-mail: [email protected].