Abstract • 124

We studied the in vitro effect of G/GM-CSF on neutrophil chemotaxis, polarization, F-actin polymerization and superoxide anion generation in 50 neonates as compared to 45 adults. We found that G-CSF and GM-CSF significantly enhanced the in vitro neutrophil chemotaxis of newborn infants, normalizing their chemotactic defect [from 35 ± 17 cells/field to 49±22 cells/field with G-CSF and to 55 ± 18 cells/field with GM-CSF, p<0.0005]. The reduced polarization of neonatal versus adult cells (71±11% vs 86±7%, p<0.03), was corrected by CSF-priming (87±10% with G-CSF and 92±5% with GM-CSF). Also the neutrophil superoxide generation, and polymerization (Relative F-actin content) significantly improved in both groups following the CSF-priming. GM-CSF priming was significantly more potent than G-CSF only in the neutrophil superoxide release. Although antibiotic therapy remain the first line of treatment in neonatal sepsis, this study reinforce the fact that supportive therapy with CSF not only improve neutrophil counts but also improve neutrophil functions.