Neutrophil CD64 in early-onset neonatal sepsis

Abstract

Background: Neonatal sepsis is a life threatening disease with an incidence of 3.5 to 8 cases per 1,000 live births; and mortality rate 16 to 30%. Cytokines, produced by monocytes, macrophages, and endothelial cells in response to infectious stimuli are important proinflammatory mediators in the early phases of the sepsis syndrome. Elevated serum levels of interleukin-6 (IL-6) had been found in both neonatal and adult sepsis. However, for neonatal sepsis, little is known about a group of molecules playing a central role in the innate immune system. Among them is the neutrophil CD64 which is expressed on neutrophil surface in many inflammatory conditions. Objective: To study the neutrophil CD64 expression in neonates with early onset sepsis and its relation to other laboratory markers as IL6, CRP, total leucocytic count and platelet count. Methods: This study comprised 30 neonates with a gestational age of 28 to 40 weeks with a picture of early onset neonatal sepsis within 48 hours of life admitted to neonatal care unit, Suzan Mubarak Hospital, El-Minia University, Egypt during the period from February, 2008 to January, 2009 and 20 healthy neonates age and sex matched as a control group. Neutrophil surface expression of CD64 was quantified with flow cytometry. We measured plasma IL6, C-reactive protein, complete blood count and blood culture. Results: Neutrophil CD64 expression was increased significantly in neonates with neonatal sepsis than controls (p=0.001). Cases with history of premature rupture of membranes (PROM) ≥48 hours, with positive blood culture or poor outcome had the highest levels of neutrophil CD64 expression (528±50.7, 558±58.4 and 560.9±43.9 relative fluorescence units (RFU) respectively). A significant positive correlation was found between CD64 levels and the levels of IL6 (r=0.71, p=0.001),C-reactive protein (r=0.74, p=0.001) and total leucocytic count (r=0.76 ,p=0.01) and negative correlation with gestational age (r=-0.92, p=0.001) and body weight (r=-0.92, p=0.006), but there was no correlation between it and platelet count (r=-0.32, p=0.08). Conclusion: Neutrophil CD64 expression is increased in neonates with early-onset neonatal sepsis and correlated well with other laboratory markers of sepsis.

Keywords: Neonatal sepsis, Cytokines, Neutrophil CD64, IL6, PROM

Egypt J Pediatr Allergy Immunol 2010;8(1):19-25