Definition and evaluation of engraftment and chimerism

Myeloid engraftment, complete donor chimerism, and primary and late graft failure (GF) were defined in a previous report.⁴ Poor graft function (PGF) is cytopenia in ⩾2 hematopoietic lines (neutrophil count <1.5 × 10⁹ L^–1, platelet count <30 × 10⁹ L^–1, and hemoglobin (Hb) <8.5 g dL^–1) for ⩾2 consecutive weeks beyond day +14 following documented engraftment in the presence of full donor chimerism, the absence of severe GvHD, CMV reactivation, relapse or drug-related myelosuppression, and hypocellular bone marrow.¹² The incidence and severity of GvHD were evaluated according to a National Institutes of Health (NIH) consensus conference on the determination of GvHD grade.¹³ Cytomegalovirus (CMV) infection and pneumonia were defined according to the literature.^14,15 Epstein–Barr virus (EBV) infection and EBV-associated post-transplant lymphoproliferative disorders (PTLD) were defined in previous reports.^16,17