Granulocyte colony-stimulating factor downregulates interferon-gamma receptor expression and stimulates interleukin-6 production in activated human macrophages.

We studied direct effects of human granulocyte colony-stimulating factor (G-CSF) on phenotypical properties of human macrophage cells in vitro. CD14⁺ monocyte/macrophages (Mc/Mphs) were isolated from blood of healthy donors by positive magnetic separation. G-CSF (0.01-1.0 ng/mL), when added to Mc/Mphs along with lipopolysaccharide (LPS, 1.0 μg/mL), was able to noticeably reduce proportions of CD119 (interferon-γ receptor 1)-positive cells, with no stable effects on CD16 (FcγRIII)⁺ and СD124 (IL-4 receptor subunit alpha)-positive cells. In addition, G-CSF markedly upregulated IL-6 production by LPS-activated Mph cells, without significantly affecting IL-1β, IL-10 and tumor necrosis factor-α (TNF-α) secretion. Our data suggests that G-CSF could restrain Mph polarization to pro-inflammatory (M1) phenotype, thus potentially supporting pro-regenerative Mph activity with implications for immunotherapeutic interventions.