1. Immunology and Allergology Laboratory Unit, S. Giovanni di Dio Hospital, 50143 Florence, Italy
2. Department of Microbiology, Immunology and Transplantation, University of Leuven, 3000 Leuven, Belgium
3. Department of Laboratory Medicine, OLV Hospital, 9300 Aalst, Belgium
4. Rheumatology Unit, S. Giovanni di Dio Hospital, 50143 Florence, Italy
5. Department of Clinical and Experimental Medicine, University of Florence, 50139 Florence, Italy
6. Department of Laboratory Medicine, University Hospital Leuven, 3000 Leuven, Belgium
7. Rheumatology Unit, Department of Medicine and Surgery, University of Perugia, 06122 Perugia, Italy