A donor graft derived from allogeneic filgrastim (granulocyte-colony stimulating factor; G-CSF)-mobilized peripheral blood cells (MPBC) that have been incubated with the recombinant human Fas ligand (FasL) APO010 ex vivo, and that can potentially be used for immune reconstitution purposes. The incubation of the hematopoietic stem cell graft with the apoptotic mediator Fas ligand (FasL) selectively induces apoptosis of mature T-cells which express high levels of Fas receptor, such as T stem cell memory (TSCM), T central memory (TCM), and T effector memory (TEM) cells and the pro-inflammatory T-helper cells (Th) Th1 and Th17 subsets while sparing CD34-positive stem and progenitor cells. Upon washing and further ex vivo preparations, and upon allogeneic hematopoietic stem cell transplantation (HSCT) with the FasL-treated allogeneic MPBCs, these cells provide hematopoietic cell recovery, preserve the graft-versus-leukemia (GvL) effects, and may prevent graft-versus-host disease (GvHD).