1. Department of Immunology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Okinawa 903-0215, Japan
2. Department of Microbiology and Immunology, Drexel Institute for Biotechnology & Virology Research, Drexel University College of Medicine, 3805 Old Easton Road, Doylestown, PA 18902, USA
3. Department of Hematology, Atomic Bomb Disease Institute, Graduate School of Biomedical Science, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
4. Department of Immunology, Wright-Fleming Institute, Imperial College London, London W2 1PG, UK