Selvakumar A., et al., 1997, Immunol. Rev. 155:183-196. Wilson M.J., et al., 1997, Tissue Antigens 49:574-579. Maenaka K., et al., 1999, Structure 7:391-398. Vitale,M. et al., 2004, Int Immunol. 16 (10):1459-66. Yu M.-C., et al., 2008, Nat. Immunol. 9:898-907.