Systemic inflammation and CD11b expression by neutrophils in preterm newborns with respiratory distress syndrome not treated by surfactant

Abstract

Objectives: To evaluate CD11b expression by neutrophils in the first 12 hours of life in preterm newborns with respiratory distress syndrome (RDS) as a marker of systemic inflammation and an indicator for severity of illness.

Subjects and methods: In this prospective case-control study, we obtained peripheral blood samples from subjects during the first 12 hours of life. We measured CD11b expression by neutrophils using flow cytometry. Surfactant was not used for treatment of RDS due to economic reasons. The clinical severity of RDS was graded into 4 sub-categories based on the initial radiographic findings. Expression of CD11b was compared between groups. Correlation analyses between CD11b, RDS severity, and clinical outcomes were done using spearman correlation coefficient.

Results: We studied 60 preterms with RDS (Cases) and 30 Controls. CD11b expression was significantly increased in Cases compared to Controls and differed significantly among the 4 radiological sub-categories within Cases; the highest being in RDS grade 4 and lowest in RDS grade 1. CD11b expression was significantly higher among RDS neonates who received mechanical ventilation compared to those who did not, and in neonates who developed bronchopulmonary dysplasia (BPD) or died compared to those who did not. CD11b expression in Cases was negatively correlated with gestational age and positively correlated with the severity of RDS.

Conclusion: CD11b expression as a marker of systemic neutrophil activation is markedly increased in preterm newborns with RDS who did not receive surfactant. It can serve as an indicator for the severity of illness and adverse outcomes of RDS. The response of CD11b expression to surfactant treatment and its impact on outcomes in infants with RDS needs to be explored.