Major and minor lymphocytes subpopulations in peripheral blood and cerebrospinal fluid of children with meningitis

Abstract

Introduction. The analysis of current publications indicates at our insufficient understanding of subpopulation composition of lymphocytes in peripheral blood and cerebrospinal fluid (CSF) during pediatric neuroinfectious diseases. It has been found that the main lymphocyte populations are divided into many small (minor) subpopulations.The purpose of this research was to assess percentage of major and minor blood and CSF lymphocyte subsets in children with aseptic viral meningitis (AM) or bacterial purulent meningitis (BM).Materials and methods. Phenotyping of blood and CSF lymphocytes of children aged from 4 months to 17 years diagnosed with AM (n = 86) and BM (n = 39) was carried out by using flow cytometry. As a comparison group, we analyzed peripheral blood and CSF samples collected from children with acute respiratory viral infections (ARVIs) associated with syndrome of meningism (n = 27). There was evaluated percentage of the major cell subpopulations (CD3+ T-lymphocytes, T-helpers — CD3+CD4+ Th, cytotoxic T-lymphocytes — CD3+CD8+ CTL, natural killer cells — CD3-CD16+CD56+ NK, B-cells — CD3-CD19+), as well as minor lymphocyte subsets (double positive (DP) (CD3+CD4+CD8+), double negative (DN) (CD3+CD4-CD8-) T-cells, NKT (CD3+CD16+CD56+), CD3-CD8+ NK, CD3+CD8dim and CD3+CD8 8bright).Results. It was found that the acute period of BM and AM vs. the comparison group (ARVI) was characterized by significant differences in the blood and CSF composition of major and minor lymphocyte subsets. In particular, blood T-cells, Th, CTL, NK, NKT, DN, CD3-CD8+ NK, CD3+CD8bright and CD3+CD8dim dominated in parallel with significantly lowered B-cell frequency in AM vs. BM. In the CSF of children with AM, T-cells and Th prevailed, whereas count of B-cells and CD3-CD8+ NK was lower compared to those in BM. In addition, further differences were revealed in CSF and blood cell subset composition depending on nosological entity, while maintaining differences in some major and minor lymphocyte subpopulations lacked in the comparison group. Calculating the CSF/blood ratio for the major and minor lymphocyte subsets uncovered the prevalence for the majority of cell subpopulations (the coefficients ranged from 1.2 to 16.4) in the CSF of the comparison group (ARVI), except B-cells, NK and CD3-CD8+ NK (coefficients ranged from 0.07 to 0.31). AM and BM were featured with various changes in the CSF/blood ratio found for most of the studied subpopulations in the acute period as well as the recovery phase highlighted with characteristic traits for each nosological form.Conclusion. The data obtained indicate about finding specific features in the activation of systemic and intrathecal immune response during viral and bacterial meningitis in children, which may be used as an additional differential diagnostic criterion.