1. Department of Immunology and Medical Zoology1 and
2. Laboratory of Host Defenses, Institute for Advanced Medical Sciences,2 Hyogo College of Medicine, Nishinomiya, Hyogo 663-8501,
3. Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, Tokyo,3 Japan
4. Department of Host Defenses, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871,4
5. Laboratory Animal Research Center, Institute of Medical Science, University of Tokyo, Tokyo 108-8639,5 and