1. Department of Immunology, Faculty of Medicine
2. Doctoral Program in Graduate School of Comprehensive Human Sciences and
3. Life Science Center of Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, 1-1-1, Ten-nodai, Tsukuba, Ibaraki 305-8575, Japan
4. Cell Engineering Division, RIKEN BioResource Center, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan