1. Assistance Publique-Hopitaux de Paris, Hospital Saint Louis, Division of Hematology/Immunology/Oncology, Hematology Transplantation, Paris, France;
2. University Paris VII, Denis Diderot, Paris, France;
3. INSERM U1160, Team GVHD and Allogeneic Transplantation, Paris, France;
4. Dana-Farber Cancer Institute, Boston, MA; and
5. Harvard Medical School, Boston, MA