1. Department of Microbiology and Immunology; Showa University School of Medicine; Shinagawa-ku Tokyo 142-8555 Japan
2. Department of Developmental Medical Sciences, Graduate School of Medicine; The University of Tokyo; Bunkyo-ku Tokyo 113-0033 Japan
3. Division of Hematology, Department of Internal Medicine; Juntendo University School of Medicine; Bunkyo-ku Tokyo 113-0033 Japan
4. Institut für Physiologische Chemie; Universität; Duesbergweg 6 55099 Mainz Germany