20?10 9 /L was (18 1?3 0) days in the recipients.The incidences of grade I GVHD and II GVHD were 28 6% and 5 7%, respectively. Furthermore, the percentages of CD34 + and CD4 + cells in G CSF stimulated bone marrow increased, concomitant with a significant decline in CD8 + cell count. These data demonstrated that G CSF mobilization remodeled the density of hematopoietic progenitors and T lymphocyte subsets in the bone marrow, which in turn accelerated hematopoietic reconstitution and minimized the incidence of severe acute GVHD after allogeneic transplantation.Transplantation of marrow harvests from donors who are pretreated with G CSF might be a feasible measure for a successful allogeneic bone marrow transplantation.