Abstract 1844

Objectives: Activation of polymorphonuclear neutrophils (PMN) may play a role in the pathogenesis of respiratory distress syndrome (RDS). We evaluated the relationship between perinatal events and indicators of phagocyte activation in plasma and tracheal aspirate fluid (TAF) in preterm infants during the early postnatal period. Study design: 48 ventilated preterm infants (GA 27.6±1.9 wks, BW 968±276 g) were studied during d 1-7. 16 were born to mothers with premature rupture of the membranes (PROM), 6 of them were exposed to chorioamnionitis, and 4 had signs of neonatal infection. As marker of neutrophil activation human neutrophil lipocalin (HNL) was measured in plasma and in TAF, and as marker of monocyte activation lysozyme (LZM) was measured in plasma. Results: Plasma and TAF HNL peaked on d 3, whereas plasma LZM increased to a maximum on d 5. In infants born to mothers with PROM plasma HNL (P=0.016), TAF HNL (P=0.0004), and plasma LZM (P=0.0001) were higher during the first week. These differences were present already on d 1 (all P<0.05). In infants born to mothers treated with betamethasone plasma HNL was lower (P=0.005) than in infants whose mothers did not receive this treatment. Conclusions: Early phagocyte activation is seen in preterm infants born to mothers with PROM. In the newborn PROM may induce systemic and pulmonary inflammation even without clinical signs of infection. Antenatal betamethasone reduces neutrophil activation in the preterm infant.