EFFECT OF RHG-CSF ON THE MOBILIZATION OF CD38 AND HLA-DR SUBFRACTIONSOF CD34-BLOOD PROGENITOR CELLS( PERIPHERAL)

Several studies have demonstrated that both CD34+/CD38- and CD34+/HLA- DR- human hematopoietic progenitor cells have properties associated wi th hematopoietic stem cells. However, the kinetics of these two cell p opulations in human peripheral blood (PB) after priming with granulocy te colony-stimulating factor (rhG-CSF) has not been investigated. By u sing flow-cytometric analysis we have shown that administration of rhG -CSF to 14 patients eligible for peripheral blood progenitor cell (PBP C) transplantation led to an increment of CD34+/CD38+ and CD34+/HLA-DR + cells in the PB that paralleled the increase of total CD34+ cells, i ndicating that such subpopulations are responsible for the major relea se of CD34+ cells. Furthermore, rhG-CSF priming led to a significant m obilization of fractions of more immature CD34+/CD38- and CD34+/HLA-DR - cells to the PB. In the leukapheresis preparations, the average freq uency of CD34+ cells lacking the CD38 or HLA-DR antigens was low (5% a nd 30%, respectively), with little overlap between the CD38- and HLA-D R- subpopulations. In addition, the yield of each subset of CD34+ cell s (CD34+/CD38+ and CD34+/HLA-DR+/-) in the PB correlated with the numb ers in the collected material. The results of the present study indica te that administration of rhG-CSF causes a significant increase of CD3 4+/CD38+/- and CD34+/HLA-DR+/- cells in PB, and that such cells can be then safely harvested by leukapheresis procedures.