In vivo administration of granulocyte colony-stimulating factor increases the surface expression of sialyl-Lewis(x) on neutrophils in healthy volunteers.

We examined the in vivo effect of granulocyte colony-stimulating factor (G-CSF) on the surface expression of putative counterligands for endothelial selectins on neutrophils in healthy volunteers. G-CSF (50 microg/m2/day) was administered subcutaneously to 5 healthy volunteers for 4 days. The expression of surface antigens on neutrophils was determined by flow cytometry and monoclonal antibodies. G-CSF administration increased the number of leukocytes, mainly of neutrophils, which was associated with an increase in the expression of the high-affinity Fc receptor for IgG (FcRI, CD64) and CD14 on neutrophils. G-CSF administration decreased the surface expression of L-selectin on neutrophils, whereas it increased the expression of sialyl-Lewisx but not Lewisx on neutrophils. These findings suggest that G-CSF participates in the neutrophil-endothelial cell interactions in vivo by modulating the expression of adhesion molecules and ligands for endothelial selectins on neutrophils.