Changes in <i>in vitro</i> GM-CSF-exposured monocyte subset composition and phagocytic activity in children with infectious mononucleosis

Abstract

The aim of the study was to investigate the features of changes in the monocytes subset composition and phagocytic activity in children with infectious mononucleosis (IM) exposed to granulocyte-macrophage colony-stimulating factor (GM-CSF) in vitro. We examined 84 children aged 3 to 11 years with EpsteinBarr virus (EBV) infection diagnosed by clinical signs, positive EBV DNA test in blood lymphocytes and ELISA data (EBV-VCAIgM (+), EBV-EA-DIgG (+)). The control group consisted of 40 apparently healthy age-matched children. Monocytes were obtained by the standard method on adhesion to plastic from mononuclear cells isolated from heparinized venous blood by density gradient centrifugation. The isolated monocytes were divided into two samples: control (without GM-CSF) and experimental (50 ng of GM-CSF per 1 ml of cell suspension). The monocyte subset composition and phagocytic activity in both samples were measured by flow cytometry after 1-hour incubation at 37C ina CO2-incubator. It was found that in children with progressing IM, the blood monocyte subpopulation composition changes and their phagocytic activity is impaired. It was found that the subset composition and phagocytic activity of the blood monocytes changed in children during development of IM. Changes in the subset composition of monocytes in acute IM did not depend on the age group of children (36 and 711 years) and were characterized by increased number of pro-inflammatory (intermediate) monocytes and decreased level of anti-inflammatory (non-classical) monocytes. Features of altered monocyte phagocytic activity in children with IM depended on age. The phagocytic activity of all three monocyte subsets was reduced in children with IM 36 years old while children with IM 711 years old had reduced phagocytic activity only in intermediate and non-classical monocytes. The effect of GM-CSF in vitro on monocytes in patients with IM, regardless of the age of children, led to significantly increased level of anti-inflammatory monocytes while the phagocytic activity of cells changed less. An increase in the phagocytic number for classical monocytes after incubation with GM-CSF in vitro was noted in children with IM at the age of 36 years while the phagocytic index of this fraction of monocytes remained unchanged. The level of the phagocytic index increased only in classical monocytes of children with IM aged 711 years. The presented results determine the scientific and clinical value of studying the mechanisms of the effect of GM-CSF on cells of the immune system and prove that this cytokine can be used in a new immunotherapeutic strategy for the treatment of IM.