FACTORS THAT INFLUENCE THE COLLECTION AND ENGRAFTMENT OF ALLOGENEIC PERIPHERAL-BLOOD STEM-CELLS IN PATIENTS WITH HEMATOLOGIC MALIGNANCIES

Purpose: To determine the number of CD34(+) cells associated with a hi gh probability of rapid engraftment after allogeneic peripheral-blood stem-cell (PBSC) transplant, and to examine the relationship between c ertain donor characteristics and the effectiveness of PBSC mobilizatio n. Patients and Methods: Between December 1994 and July 1996, we treat ed 47 patients who had resistant hematologic neoplasms with myeloablat ive therapy followed by transplantation of allogeneic PBSC collected f rom histocompatible siblings after mobilization with granulocyte colon y-stimulating factor (G-CSF). Expression of CD34 was determined by flo w cytometry. Results: Engraftment was rapid and similar to that observ ed following autologous PBSC transplant, with an absolute neutrophil c ount (ANC) greater than 500/mu L and platelet count greater than 20,00 0/mu L on median days +9 and +11, respectively. The pace of hematologi c recovery correlated with the number of hematopoietic progenitors tra nsplanted, so that patients who received greater than 5 x 10(6) CD34() cells/kg recipient weight had a 95% likelihood of neutrophil and pla telet recovery by day +15. Baseline (precytokine) CD34(+) cells per mi lliliter of donor peripheral blood and total G-CSF dose (donor weight x 10 mu g/kg) correlated with the number of CD34(+) cells collected (R -2 = .24 and P = .0009, and R-2 = .24 and P < .0001, respectively). Do nor age and sex did nor effect mobilization. Conclusion: Following all ogeneic PBSC transplant, patients who received greater than 5 x 10(6) CD34(+) cells/kg recipient weight had a high probability of rapid engr aftment. Donors with low baseline levels of circulating progenitors (< 2,000 CD34(+) cells/ml blood) and those who received lower total dose s of G-CSF were less likely to be effectively mobilized. For donors wi th low baseline CD34(+) counts, higher doses of G-CSF might improve mo bilization. Baseline CD34(+) counts and total G-CSF dose accounted for less than half of the variation in CD34(+) cells collected, which ind icates that other, as yet unidentified, factors play an important role in determining the effectiveness of mobilization. (C) 1997 by America n Society of Clinical Oncology.