1. Division of Hematology, Department of Medicine Keio University School of Medicine Tokyo Japan
2. Division of Gastroenterology and Hepatology, Department of Medicine Keio University School of Medicine Tokyo Japan
3. Department of Pathology National Institute of Infectious Diseases Tokyo Japan
4. Department of Pathology Keio University School of Medicine Tokyo Japan
5. Department of Gastroenterology & Hepatology International University of Health and Welfare Narita Japan