1. Department of Hematology‐Oncology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
2. Central Research Laboratories, Chugai Pharmaceutical Company, Tokyo, Japan
3. Department of Pathology, Chiba University School of Medicine, Chiba, Japan
4. Hokkaido Red Cross Blood Center, Sapporo, Japan
5. Osaka Bioscience Institute, Osaka, Japan