Studies of immune parameters in adolescents over the period of 2020-2021

Changes of immune system in adolescents during the 2020-2021 pandemic have not been sufficiently studied. The paper concerns features of flow cytometric indexes among the children of different age groups and their immunoglobulin status. The cohort was classified into 12 categories (3 age subgroups, and 4 categories relative to immunoglobulin status). The aim of this work was to investigate changes in the immunograms among children and adolescents during the COVID pandemic evaluated by means of flow cytometry. The methodology of the present work was based on evaluation of immunograms including biochemical studies and flow cytometric analysis. The results of immunological studies of the patients were classified into three age categories. Laboratory diagnostics of human immune system was performed by means of serological and flow cytometric analyses. A total of 250 samples were analyzed in the course of the study. Primary classification of immunograms was performed by immunoglobulin A, M and G status into four categories as follows: absence of disease (R1); immunoglobulin A, M, G values within the reference ranges and active disease (R2); immunoglobulin A and M beyond the reference ranges and passive disease stage (R3); immunoglobulin G and M status and patient recovery process (R4). Eight parameters of immune cells detectable by flow cytometry were chosen for evaluation: total leukocytes, lymphocytes, T lymphocytes (CD3+), B lymphocytes (CD19+), NK cells (CD16+CD56+), T helper cells (CD3+CD4+), NKT cells, and immunoregulation index (CD4+/CD8+). Quantitative assessment of deviations for these indices from the reference values was performed in three distinct age groups under 18 years of age living in the Perm region of the Russian Federation during the pandemic of 2020-2021. The results showed that, in the R1 category, exceeding of reference values was observed for T cells and B cells in the older and younger groups. For T helper cells and immunoregulation index, the reference thresholds were exceeded in the younger groups. The R2 patients had higher leukocyte levels in the older group along with lower immunoglobulin levels. The immunoregulation index in the younger group was accompanied by higher immunoglobulin levels. T cell levels were decreased in the middle group, along with reduced immunoglobulin levels. B lymphocyte values were elevated in the middle group with decreased immunoglobulin levels. In R3 children, a decrease was observed in the immunoregulation index for the older group, with decreased immunoglobulin levels. In the R4 category, the decreased overall deviation of the main immunogram indexes was revealed.