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

Objective: To quantify platelet-neutrophil interaction by flow cytometry, in newborn cord blood, as a function of gestational age. Rationale: Little is known about platelet function markers in the newborn, and developmental variations in these markers are not well described. Methods: 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. Results: 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. Conclusions: 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.