1. Department of Medicine 'B' and the Research Unit of Autoimmune Diseases, Sheba Medical Center, Tel-Hashomer, and Tel-Aviv University, Israel
2. Speciality Laboratory, Santa Monica, CA, USA
3. Rheumatology Service, Sheba Medical Center, Israel
4. Department of Connective Tissue Diseases, Institute of Rheumatology, Warsaw, Poland
5. Rambam Medical Center, Haifa, Israel
6. Department of Medicine 'B' and the Research Unit of Autoimmune Diseases, Sheba Medical Center, Tel-Hashomer, and Tel-Aviv University, Israel;