Enhanced survival but reduced engraftment in murine recipients of recombinant granulocyte/macrophage colony-stimulating factor following transplantation of T-cell-depleted histoincompatible bone marrow

In vivo administration of murine recombinant granulocyte/macrophage colony stimulating factor (rGM-CSF) was evaluated for effects on survival and engraftment in an allogeneic murine bone marrow transplantation (BMT) model involving T-cell depletion of donor marrow. The model provides a high incidence of graft failure/rejection. Recipients of continuous subcutaneous infusions of rGM-CSF had a significant survival advantage when compared with untreated controls. However, a significantly lower incidence of donor cell engraftment was noted. Hematological parameters were not substantially affected. When rGM-CSF was administered intraperitoneally (IP), twice daily injections closely approximated the effects of continuous infusion on survival. Single IP injections were without significant effects on survival or engraftment. These results demonstrate that prolonged frequent in vivo exposure to rGM-CSF can significantly improve survival but significantly decreases donor cell repopulation in recipients of T-cell-depleted histoincompatible marrow grafts.