Abstract 1

Background: Neutrophil activation is associated with tissue injury. Subjects: - As indicator of neutrophil activation we measured expression of CD11b/CD18 on neutrophils in healthy adults, and in cord blood and in blood samples during postnatal days 1-5 in preterm (GA 27.7±2.2 wks) and term infants.

Results: In preterm infants (N=10) the expression in cord blood was 109±25 RFU, and in term infants (N=29) 119±11 RFU; in 29 adult controls it was 110±32 RFU. On d 1 in preterm infants with RDS the expression was 161±44 (N=29), and during d 2-5 165±51 RFU (N=47), and in term infants during d 2-5 119±10 RFU (N=10). In preterm infants the expression was higher on d 1 (p=0.0036) and d 2-5 (p=0.0005) than in cord blood; during d 2-5 it was higher than in term infants (p=0.0018), and in adults (p=0.0001).

Conclusions: Neutrophil activation may play a role in the morbidity of the preterm infant with RDS.