1. Division of Hemopoiesis, Institute of Hematology and Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Tokyo, Japan
2. Division of Hemopoiesis, Institute of Hematology and Department of Internal Medicine, Jichi Medical School, Tochigi, Japan
3. Division of Hemopoiesis, Institute of Hematology, Jichi Medical School, Tochigi, Japan
4. Department of Internal Medicine, Jichi Medical School, Tochigi and Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Tokyo, Japan