1. School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8501, Japan
2. Tsukuba Biotechnology Research Center, 5-2-3, Tokodai, Tsukuba-shi, Ibaraki 300-2698, Japan
3. Department of Infection and Immunity, School of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-Shi, Tochigi, 329-0498, Japan
4. Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan