Absolute Neutropenia and Infection Development in Premature Infants in Early Neonatal Period: Cross-Sectional Study

Background. Premature infants have high risk of developing of neutropenia and infections in the early neonatal period. The correlation of these events requires further studies.Objective. The aim of the study was to investigate the frequency of absolute neutropenia and infectious complications cases in premature infants in the early neonatal period with estimation of phenotypical and functional features of cord blood neutrophils.Methods. The study included premature infants (gestational age 25–36 weeks) with APGAR score < 8 on the 1st and 5th minutes of life. The frequency of absolute neutropenia (at least once < 1.5109/l) and infectious complications (localized infections of bacterial etiology, early neonatal sepsis) cases in the first 14 day of life was analysed. Additionally, we have determined the expression of CD64, CD16, CD32 by cord blood neutrophils in premature (n = 102) and mature infants (n = 30) via method of flow cytofluorometry. We have used FITC labeled Escherichia coli to estimate their phagocytic activity, and stimulation of E. coli neutrophils in the presence of 5 mM of dihydrorhodamine 123 to estimate their stimulation index (ratio of mean fluorescent intensity (MFI) of activated neutrophils in stimulated samples and in negative controls, E. coli free samples).Results. The episodes of absolute neutropenia in the first 14 days of life were recorded in 17 cases, infectious complications — in 87 children (in 24 cases — sepsis) in the group of premature infants. The frequency of infectious complications in premature children did not correlate with the frequency of absolute neutropenia episodes. Cord blood neutrophils in premature infants had higher CD64 expression and, on the contrary, lower CD16 expression, as well as low phagocytic activity and stimulation index value (in all cases p < 0.001).Conclusion. Absolute neutropenia in premature infants in early neonatal period does not correlate with high risk of bacterial infections. However, cord blood neutrophils in premature infants had lower functional activity.