[1] Univ Massachusetts, Med Ctr, Program Mol Med, Worcester, MA 01605 USA
[2] Univ Massachusetts, Sch Med, Howard Hughes Med Inst, Worcester, MA 01605 USA
[3] Univ Vermont, Dept Med, Immunobiol Program, Burlington, VT 05405 USA
[4] Yale Univ, Sch Med, Howard Hughes Med Inst, New Haven, CT 06520 USA
[5] Yale Univ, Sch Med, Dept Immunobiol, New Haven, CT 06520 USA