Granulocyte colony-stimulating factor and lineage-independent modulation of VLA-4 expression on circulating CD34(+) cells

Although the use of allogeneic transplants of peripheral blood stem/progeni tor cells (PBSCs) is increasing, the precise mechanism of PBSC mobilization has not yet been fully clarified. We examined the expression of some adhes ion molecules on CD34(+) cells from steady-state bone marrow (BM), granuloc yte colony-stimulating factor (G-CSF)-mobilized PBSCs, and cytotoxic drugs plus G-CSF-mobilized PBSCs. Irrespective of mobilization method, very late antigen (VLA)-4 expression on circulating CD34(+) cells was significantly l ower than on steady-state BM CD34(+) cells. To elucidate the influence of l ineage commitment on VLA-4 expression of circulating CD34(+) cells, we anal yzed VLA-4 expression on different subsets of CD34(+) cells with or without CD33, CD38, CD5, or CD10 antigens, or Glycophorin A in G-CSF-mobilized PBS Cs and steady-state BM from related donors, using 3-color flow cytometry VL A-4 on circulating CD34(+) subsets was less expressed than on each correspo nding subset of steady-state BM CD34(+) cells. Furthermore, VLA-4 positive rates showed no significant difference among the CD34(+) subsets. Finally, the data comparing CD34(+) cells from steady-state and G-CSF-mobilized PBSC s revealed no differences in terms of VLA-4 expression. These data suggest that reduced expression of VLA-4 may be a result of peripheralization of CD 34(+) cells from bone marrow, which occurs in a G-CSF- and lineage-independ ent fashion. Int J Hematol. 2000;71:328-333. (C) 2000 The Japanese Society of Hematology.