In vivo administration of granulocyte colony-stimulating factor promotes neutrophil survival in vitro

Abstract: We recently showed that recombinant human granulocyte‐colony stimulating factor (rhG‐CSF) maintained the viability of human neutrophils in incubation for up to 72 hours. However, it is not known whether rhG‐CSF can enhance neutrophil survival in in vivo situations. To clarify this issue, we investigated neutrophil survival in vitro following in vivo injection of rhG‐CSF. Neutrophils were obtained from 4 pediatric patients with malignancies and healthy adult volunteers before and after rhG‐CSF administration. Neutrophils obtained before rhG‐CSF treatment started to undergo apoptosis after 24 h of incubation. In contrast, the survival of neutrophils drawn after rhG‐CSF administration increased by approximately 24 h. Concomitantly, the appearance of typical ladder‐like DNA fragmentation was delayed. Such an increase in neutrophil survival was inhibited by coincubation with either H 7 (10 μmol/1) or H 8 (20 μmol/1), which worked as protein kinase C inhibitors. Although our study did not measure neutrophil survival in vivo directly, it provides us with further evidence that rhG‐CSF may function to prolong neutrophil life expectancy in vivo .