CD34(+) CELL DOSE PREDICTS SURVIVAL, POSTTRANSPLANT MORBIDITY, AND RATE OF HEMATOLOGIC RECOVERY AFTER ALLOGENEIC MARROW TRANSPLANTS FOR HEMATOLOGIC MALIGNANCIES

After autologous or allogeneic transplants of peripheral blood stem ce lls (PBSC), an adequate dose of CD34(+) cells is necessary to ensure e arly and sustained hematopoietic engraftment and favorable clinical ou tcome. There are no comparable data on the relationship between CD34() cell dose and recovery after allogeneic bone marrow transplants (BMT ). Twenty-eight patients with hematologic malignancies received a BMT from an HLA-identical sibling, using T-cell depletion and cyclosporin for graft-versus-host disease prophylaxis and delayed donor lymphocyte transfusions in an attempt to prevent leukemia relapse, The treatment -related mortality (TRM), primarily due to infections and cytopenias, was significantly higher for 13 patients receiving less than 1 x 10(6) CD34(+) cells/kg (64.9% +/- 12.8% v 6.9% +/- 6.4%, P =.003). Survival at a median follow-up of 1 year was also lower in the group receiving less than 1 x 10(6) CD34(+) cells/kg (30.8% +/- 12.8 v 74.3% +/- 13.7 %, P =.005). The CD34(+) cell dose was the only variable significantly associated with TRM. The dose of CD34(+) cells also correlated with s peed of hematopoietic recovery. Patients receiving more than 2 x 10(6) CD34(+) cells/kg showed significantly earlier recovery of monocytes a nd a trend for earlier recovery of lymphocytes. They achieved platelet and red blood cell transfusion independence earlier, required less gr anulocyte colony-stimulating factor support during ganciclovir treatme nt, and spent fewer days in the hospital after transplantation. These results suggest that, for allogeneic T-cell-depleted BMT, the higher C D34(+) cell doses may improve outcome in engrafting patients.