HARVESTING AND ENRICHMENT OF HEMATOPOIETIC PROGENITOR CELLS MOBILIZEDINTO THE PERIPHERAL-BLOOD OF NORMAL DONORS BY GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR (GM-CSP) OR G-CSF - POTENTIAL ROLE IN ALLOGENEIC MARROW TRANSPLANTATION

To explore the use of stem/progenitor cells from peripheral blood (PB) for allogeneic transplantation, we have studied the mobilization of p rogenitor cells in normal donors by growth factors. Normal subjects we re administered either granulocyte-macrophage colony-stimulating facto r (GM-CSF) at 10 mu g/kg/d, or G-CSF at 10 mu g/kg/d, or a combination of G- and GM-CSF at 5 mu g/kg/d each, administered subcutaneously for 4 days, followed by leukapheresis on day 5. Mononuclear cells express ing CD34 (CD34(+) cells) were selectively enriched by affinity labelin g using Dynal paramagnetic microspheres (Baxter Isolex; Baxter Healthc are Corp, Santa Ana, CA). The baseline CD34(+) cells in peripheral blo od before mobilization was 0.07% +/- 0.05% (1.6 +/- 0.7/mu L; n = 18). On the fifth day after stimulation (24 hours after the fourth dose), the CD34(+) cells were 0.99% +/- 0.40% (61 +/- 14/ mu L) for the 8 sub jects treated with G-CSF, 0.25% +/- 0.25% (3 +/- 3/mu L, both P < .01 v G-CSF) for the 5 subjects administered GM-CSF, and for the 5 subject s treated with G- and GM-CSF, 0.65% +/- 0.28% (41 +/- 18/mu L, P < .5 v GM-CSF). Parallel to this increase in CD34(+) cells, clonogenic assa ys showed a corresponding increase in CFU-GM and BFU-E. The total numb er of CD34(+) cells collected from the G-CSF group during a 3-hour aph eresis was 119 +/- 65 x 10(6) and was not significantly different from that collected from the group treated with G- and GM-CSF (101 +/- 35 x 10(6) cells), but both were greater than that from the group treated with GM-CSF (12.6 +/- 6.1 x 10(6); P < .01 for both comparisons). Ana lysis of the CD34(+) subsets showed that a significantly higher percen tage of cells with the CD34(+)/CD38(-) phenotype is found after mobili zation with G- and GM-CSF. In the G-CSF group, immunomagnetic selectio n of CD34(+) cells permitted the enrichment of the CD34(+) cells in th e apheresis product to 81% +/- 11%, with a 48% +/- 12% yield and to a purity of 77% +/- 21% with a 51% +/- 15% recovery in the G- GM-CSF gro up. T cells were depleted from a mean of 4.5 +/- 2.0 x 10(9) to 4.3 +/ - 5.2 x 10(6) after selection, representing 99.9% depletion. We conclu de that it is feasible to collect sufficient numbers of PB progenitor cells from normal donors with one to two leukapheresis procedures for allogeneic transplantation. Subjects treated with the combination of G - and GM-CSF showed an equivalent mobilization of CD34(+) cells and CF U-GM as G-CSF alone, and also demonstrated a significantly greater mob ilization of cells with the CD34(+)/CD38(-) phenotype. (C) 1995 by The American Society of Hematology.