Abstract 48

Background. Reports on neonatal neutrophil function are equivocal. This study compares the neutrophil respiratory burst activity (NRBA), indicative of bacterial killing activity, of healthy neonates directly with healthy adult volunteers. The response to priming with granulocyte-colony stimulating factor (G-CSF) and granulocyte macrophage-colony stimulating factor (GM-CSF) was measured in each population to determine additional functional capacity and therapeutic potential.

Method. Term cord blood (n=20), or at 1-3 weeks of age (n=25; mean gestation 34 wks; mean age 14d) from healthy babies were taken and tested simultaneous to adult samples. A whole blood flow cytometry technique was used to measure NRBA after incubation with or without the CSFs. Median fluorescence was measured.

Results. Neonatal and cord NRBA were 470% and 87% (both p<0.001) greater than adult NRBA, respectively. Priming with G-CSF resulted in increases above each population's control NRBA for adult/neonatal/cord blood of 18% (p=0.01)/ 18% (p=0.02)/ 65% (p<0.001) and for GM-CSF 95% / 78% / 202% (all p<0.001).

Conclusion. Neutrophils from healthy neonates produce a greater bacterial killing activity than those from healthy adult volunteers yet retain an equal potential to priming by the colony stimulating factors. In this respect neonatal neutrophil function is not impaired.