Apoptosis of cord blood neutrophils and their response to colony-stimulating factors

Neutrophil production and functions are immature in newborns. Although neutrophil kinetics during neonatal period have been widely studied, little is known about the effect of apoptosis on these defects. In this study, we examine the apoptosis of neonatal neutrophils and the effects of colony-stimulating factors (CSF) on this process. The study was performed using three different methodologies (morphological analysis, surface Fas expression, and mitochondrial 7A6 antigen expression) and the results were compared with adult controls. Neonatal neutrophils more rapidly underwent apoptosis in comparison to adult neutrophils. The above-mentioned three different methods gave similar results. Granulocyte-CSF (G-CSF) and granulocyte-macrophage CSF (GM-CSF) decreased the apoptosis of neutrophils in newborns and adults. This effect was significantly more pronounced in adults than newborns in morphological analysis. Increased apoptosis may contribute to qualitative and quantitative defects of neutrophils during neonatal period and may be an explanation for the proneness of newborn to develop neutropenia during systemic infections.