Granulocyte colony-stimulating factor receptor expression on neutrophils of term and preterm neonates with and without signs of infection

Neutrophils are an essential component of the human host defence system against infection. Recombinant human granulocyte colony-stimulating factor induces neutrophilia and enhances effector functions of mature neutrophils, Since the biological effects of granulocyte colony-stimulating factor (G-CSF) are mediated by its receptor, we investigated the expression of G-CSF receptor on the surface of neutrophils of term and preterm neonates (n = 22) with and without signs of infection and of healthy adults (n = 13) by flow cytometry. In healthy adults, the percentage of neutrophils expressing G-CSF receptor was higher compared to cord blood of term and preterm neonates (87% vs 53%, P < 0.05). Between 2 and 32 h of life, neonates with signs of infection showed lower values of G-CSF receptor expression compared to neonates without signs of infection (32% vs 54%, P < 0.05). No correlation was detectable between expression of G-CSF receptor and gestational age. Conclusion Expression of granulocyte colony-stimulating factor receptor on neutrophils is lower than in adults. This may adversely affect granulopoiesis and neutrophil function during the neonatal period. Moreover, granulocyte colony-stimulating factor receptor expression seems to be down-regulated during neonatal infection.