1. Immunology and Allergology Laboratory Unit, Azienda Sanitaria di Firenze, San Giovanni di Dio Hospital, Florence, Italy
2. Department of Research, INOVA Diagnostics Inc., 9900 Old Grove Road, San Diego, CA 92131-1638, USA
3. Rheumatology Unit, Department of Internal Medicine, San Giovanni di Dio Hospital, Azienda Sanitaria di Firenze, Florence, Italy
4. Rheumatology Unit, L. Sacco University Hospital, Milan, Italy