Clinical and diagnostic significance of apoptosis in the development of neutropenia and bacterial complications in newborns with respiratory distress syndrome

Background

The development of neutropenia with neonates with RDS on mechanical ventilation is a sign of the realization of bacterial complications [1, 2]. The purpose of this study was the optimization of prevention of neonatal sepsis.

Methods

With permission of the Ethics Committee 64 full-term newborns with RDS on mechanical ventilation, without clinical signs of infection, were retrospectively divided into two groups: with a decrease in absolute neutrophil count (M <2,000 cells/mm³) after 3 to 5 days of hospitalization (I, n = 30) and non-neutropenic (II, n = 34). The survey was conducted at admission and 3 to 5 days. They were studied on the content of lymphocytes in the early (AnnexinV-FITC⁺PI^-) and late (AnnexinV-FITC⁺PI⁺) apoptosis by flow cytometry (AnnexinV⁺-labeled FITK and propidium iodide (PI⁺)-labeled PE; Saltag, USA), taking into account results on the cytometer (Beckman Coulter Epics XL, USA); the plasma level of granulocyte colony-stimulating factor (GCSF), fibroblast growth factor (FGF), anti-apoptosis soluble sFas-ligand (sFas-L) by ELISA (Victor, Finland; test system Cytimmune Sciences Inc., USA and Bender MedSystems GmbH, Austria). Points of cutoff were determined by ROC analysis. The statistical power of the study is 80% (α ≤ 0.05).

Results

At admission, it was revealed that the patients in group I have a high content of lymphocytes in the early and late apoptosis, and low levels of GCSF, FGF, sFas-L in reference to group II (α ≤ 0.05). In group I, 27 patients at 3 to 5 days developed neutropenia (M <2,000 cells/mm³) and a reduction in plasma levels of GCSF, FGF, sFas-L and an increase in lymphocyte apoptosis (α ≤ 0.05). Sepsis developed in 22 children of group I and in only five patients of group II (α ≤ 0.05). The values of cutoff (sensitivity, specificity, accuracy) for prediction of neutropenia in neonates with RDS at admission to the ICU were: for GCSF - 1,556 pg/ml (85.1%, 75.6%, 79.6%, respectively); for sFAS-L - 5,870 pg/ml (69.56%, 74.4%, 71.9%); for FGF - 25.7 pg/ml (68%, 82%, 74.4%); for early apoptosis - 9.59% (82%, 93%, 74%); and for late apoptosis - 0.56% (94.1%, 98%, 85.3%).

Conclusion

Reduction of proliferative factors (GCSF, FGF, sFas-L) and activation of apoptotic lymphocytes are markers of neutropenia and are associated with the high incidence of sepsis in infants with RDS.