The receptor apparatus of granulocyte-macrophage line cells in premature newborns: phenotypical and functional characteristics. Significance for clinical practice
The objective. To study neutrophil Fc-gamma receptor expression and the possibility of its modulation in premature newborns with bacterial infection. Patients and methods. We examined samples of umbilical blood and also peripheral venous blood of newborns collected on the 28-30th day of life. The method of flow cytometry was used to detect the level of surface expression of neutrophil Fc-gamma receptors (CD64, CD32, CD16), phagocytic activity and oxidative burst of granulocytes stimulated by fluorescent labelled Escherichia coli. Results. Blood samples of 48 children were examined, of them 10 - full-term newborns (group 1), 18 - premature newborns with ELBW and VLBW (group 2), 20 - premature newborns with LBW (group 3). CD64 expression at birth in premature children from the 2nd and 3rd groups was 7.1 MFI (5.1; 11.5) and 6.0 MFI (5.3; 9.8), respectively, which is significantly higher (p = 0.013) than in children from group 1 (4.27 MFI (2.4; 5.8)). CD16 expression at birth was lower (p = 0.021) in premature children (group 2: 80.9 MFI (58.7; 114.8); group 3: 99.7 MFI (71.3; 126.0)) as compared with full-term newborns (125.3 MFI (95.5; 144.1)) and increased by the end of the 1st month of life (group 2: 118.5 MFI (99.5; 132.2); group 3: 126.6 MFI (110.1; 129.0)). Analysis of CD32 expression did not show statistically significant differences in the groups of study. A correlation between the intensity of oxidative burst of neutrophils and gestational age has been shown (Rs = 0.67; p = 0.0005). Granulocyte cultivation in the presence of G-CSF brings about a 2.4-5-fold increase of CD16, CD32 expression and enhanced oxidative burst. Conclusion. Premature newborns are characterised by dysregulation of Fc-gamma receptor expression and functional deficiency of neutrophils. G-CSF modulates CD16 and CD32 expression on the neutrophil surface and enhances oxidative burst.