1. Department of Hematology, Saitama Medical Center, Saitama Medical University, Saitama, Japan;
2. Department of Medicine, Division of Rheumatology, Keio University School of Medicine, Tokyo, Japan;
3. Department of Pathology, Saitama Medical Center, Saitama Medical University, Saitama, Japan;
4. Department of Medicine, Division of Hematology, Keio University School of Medicine, Tokyo, Japan;
5. Department of Rheumatology and Clinical Immunology, Saitama Medical Center, Saitama Medical University, Saitama, Japan