Sargramostim in Reducing Graft-Versus-Host Disease in Patients Who Are Undergoing Donor Stem Cell Transplantation for Hematologic Cancer or Aplastic Anemia

OBJECTIVES: * Determine the efficacy of sargramostim (GM-CSF) to mobilize CD34+ hematopoietic stem cells in donors and to reduce graft-vs-host disease in patients after allogeneic stem cell transplantation (SCT) for hematologic malignancy or aplastic anemia. * Determine the safety of GM-CSF after allogeneic SCT transplantation in these patients. OUTLINE: This is a pilot study. * Donors: Donors receive sargramostim (GM-CSF) subcutaneously (SC) once daily on days 1-6. Donors undergo stem cell harvest on day 7. Donors may undergo up to 3 apheresis procedures to reach the target stem cell dose and may receive additional GM-CSF prior to each collection. * Patients: Patients receive conditioning therapy as per transplantation protocol RP98-15. Patients undergo allogeneic stem cell transplantation on day 0. Patients then receive GM-CSF SC once daily beginning on day 7 and continuing until blood counts recover. Patients are followed weekly until day 100 and then at days 180 and 360. PROJECTED ACCRUAL: A total of 10 patients and 10 donors will be accrued for this study.