1. Department of Immunology, Graduate School of Medicine and Faculty of Medicine, University of Tokyo, Hongo 7‐3‐1, Bunkyo‐ku, Tokyo 113, Japan,
2. Japan Science and Technology Agency, PRESTO program, Keihanna Plaza, 7‐1 Hikari‐dai, Seika‐machi, Kyoto, Japan,
3. Bio Signal Pathway Project, Kanagawa Academy of Science and Technology, and, Meiji Institute of Health Science, Meiji Milk Products Co. Ltd, Naruda 540, Odawara‐shi, Kanagawa 250, Japan,
4. Department of Pathology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA,
5. Department of Medical Genetics, Biomedical Research Center, Osaka University Medical School, Yamadaoka 2‐2, Suita‐shi, Osaka 565, Japan