Platelet-Neutrophil Interactions Are Lower in Cord Blood of Premature Newborns

To quantify platelet-neutrophil interaction by flow cytometry, in newborn cord blood, as a function of gestational age.

Little is known about platelet function markers in the newborn, and developmental variations in these markers are not well described.

Cord blood samples were obtained from 64 newborns between 23 and 40 weeks' gestation. The neonates were grouped into three categories: preterm (< 34 weeks' gestation, n = 21), late preterm (34 to < 37 weeks' gestation, n = 22), and term (≥37 weeks' gestation, n = 21). We monitored the expression of P-selectin and the formation of platelet-neutrophil aggregates (PNAs) by flow cytometry while using adenosine 5'-diphosphate (ADP) or thrombin receptor-activating peptide (TRAP) as agonists.

PNAs were significantly lower in preterm compared to term neonates after TRAP or ADP stimulations (11.5 ± 5.2% vs. 19.9 ± 9.1%, p < 0.001, or 24.0 ± 10.1% vs. 39.1 ± 18.2%, p = 0.008, respectively). The expression of P-selectin also tended to be lower in preterm neonates, with significant positive correlations between P-selectin expression and PNA formation.

The potential formation of PNAs correlates with gestational age. This suggests that the development of functional competencies of platelets and neutrophils continues throughout gestation, progressively enabling interactions between them.