Abstract

The role of leukocyte-endothelial cell interactions during granulocyte colony-stimulating factor (G-CSF)-induced stem cell mobilization is unclear. To examine endothelial activation during this process, we determined levels of circulating endothelial adhesion molecules in healthy donors undergoing G-CSF-mobilized stem cell collection. Plasma levels of soluble (s) E-selectin, soluble intercellular adhesion molecule-1 (sICAM-1), and soluble vascular cell adhesion molecule-1 (sVCAM-1) were serially determined by enzyme-linked immunosorbent assays in 10 healthy donors during G-CSF-stimulated stem cell mobilization. There was a significant increase in plasma levels of all three endothelial adhesion molecules (sE-selectin, p = 0.01; sICAM-1, p = 0.003; sVCAM-1, p = 0.0002) between day 1 and day 5 of G-CSF stimulation, but only sVCAM-1 concentrations exceeded the range obtained from unstimulated controls in all stem cell donors. Increases of sCAM were accompanied by increased numbers of white blood cells and CD34(+) progenitors in peripheral blood. G-CSF-stimulated peripheral blood progenitor cells (PBPC) mobilization results in increased levels of circulating endothelial adhesion molecules that were most evident for VCAM-1 molecules. Because soluble VCAM-1 remains active in binding to the VLA-4 receptor on CD34(+) cells, it may reduce stem cell adhesiveness to endothelial cells and to bone marrow microenvironment.