[1] Dana Farber Canc Inst, Dept Pediat Oncol, Boston, MA 02115 USA
[2] Dana Farber Canc Inst, Dept Pediat Hematol Oncol, Boston, MA 02115 USA
[3] Harvard Univ, Sch Med, Childrens Hosp, Boston, MA 02115 USA
[4] CNRS Marseille Luminy, INSERM, Ctr Immunol, Marseille, France
[5] MIT, Cambridge, MA 02142 USA
[6] Whitehead Inst Biomed Res, Cambridge, MA 02142 USA