Different Adhesive Characteristics and VLA-4 Expression of CD34+ Progenitors in G0/G1 Versus S+G2/M Phases of the Cell Cycle

Abstract

We identified the cell cycle status of CD34⁺ cells of steady-state bone marrow (BM) and peripheral blood (PB) obtained from healthy volunteers, and those of apherasis PB samples collected from healthy donors who had been administered granulocyte colony-stimulating factor (G-CSF). More than 10% of CD34⁺ cells in BM were in S+G₂/M phase. In contrast, regardless of whether G-CSF treatment was performed, less than 2% of CD34⁺ cells in PB were cycling. BM CD34⁺ cells showed greater VLA-4 expression and adherence to stromal cells than PB CD34⁺cells. In addition, when cycling and dormant BM CD34⁺cells were analyzed separately, the cells in S+G₂/M phase expressed more VLA-4 and adhered to the stromal cell monolayer more efficiently than the cells in G₀/G₁ phase. Furthermore, this adhesion of CD34⁺ cells to the stromal cell layer was almost completely inhibited by anti-VLA-4 antibody. Taken together, these results suggest that CD34⁺ progenitors in G₀/G₁ phase of the cell cycle differ from those in S+G₂/M phase in adhesiveness mediated by VLA-4 in the hematopoietic microenvironment. © 1998 by The American Society of Hematology.