Mature polymorphonuclear leukocytes express high-affinity receptors for IgG (Fc gamma RI) after stimulation with granulocyte colony-stimulating factor (G-CSF).

The high-affinity receptor for the constant region of immunoglobulin G IgG (Fc gamma RI; CD64) is virtually undetectable on mature polymorphonuclear neutrophils (PMNs) in healthy individuals but is expressed on PMNs in patients with certain infections and in patients treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF). The induction of Fc gamma RI by rhG-CSF has previously been reported to result from effects on immature granulocyte progenitors. To evaluate the G-CSF effect on mature PMNs, we studied the correlation between G-CSF plasma concentration and expression of Fc gamma RI on PMNs in vivo as well as the effect of G-CSF on Fc gamma RI expression on mature PMNs in vitro. Fc gamma RI expression on PMNs correlated (R = 0.79; p < .001) with plasma concentrations of endogenous or recombinant G-CSF in healthy volunteers and in patients undergoing high-dose chemotherapy and autologous bone marrow transplantation. PMNs exhibited a unimodal distribution for elevated Fc gamma RI expression, suggesting that G-CSF induced increased expression of Fc gamma RI on mature as well as on immature PMNs. In vitro, incubation of mature PMNs with G-CSF induced mRNA for Fc gamma RI. Significant Fc gamma RI surface expression was induced in a time- and dose-dependent manner. Thus, G-CSF can act on mature PMNs to increase Fc gamma RI expression and may be useful for stimulating antibody mediated immune functions of PMNs in vivo.