Cytometric features of cellular immune compartment in participants of current military conflicts

Staying in a combat area is associated with a high risk of developing mental disorders. A significant knowledge has been accumulated concerning the mechanisms of immune-mediated mechanisms of neuropsychiatric pathologies, in particular, post-traumatic stress disorder (PTSD). Activated T regulatory cells play an important role in the development of neuroinflammation under stress conditions. Our purpose was to study the indices of blood system and cytometric features of immune cellular populations in the participants of current military conflicts in presence of stress-associated adaptation disorders. We examined 97 male veterans involved in modern military conflicts, 35 to 55 years old. The main group 35 included veterans of a special military operation in Ukraine (SVO), along with 42 veterans of the second Chechen military campaign (comparison group). Control group consisted of 20 healthy persons from military staff. All patients underwent pathopsychological examination in accordance with clinical recommendations. PTSD was diagnosed in 12% of SVO veterans, whereas 77% had various types of neurotic, stress-related and somatoform disorders. In the comparison group, 2% of combatants were diagnosed with chronic personality changes. A complete blood count was performed using a standardized technique with a hematological analyzer. Immunophenotyping of lymphocytes was performed by a Navios flow cytometer (Beckman Coulter, USA). In the group of SVO veterans, we have noted a decrease in RBC volume dispersion, reduced heterogeneity index and the average volume of platelets, as well as lymphopenia and monocytosis, thus reflecting the multidirectional effect of hematopoietic regulation factors on distinct differentiation lineages of mononuclear cells. Cytometric analysis of lymphocyte populations showed a decrease in T helper cells and mature NK cells in the group of SVO veterans which explains the presence of lymphopenia and may indicate a deficiency of adaptive and innate immune response upon prolonged response to stress. We have revealed an increased number of T NK and T regulatory lymphocytes which are suggested to prevent the development of autoimmune disorders. Under stress conditions, the FoxP3 transcription factor may upregulate the glucocorticoid-induced TNF receptor in the T regulatory cells thus potentiating their proliferative activity. We have also shown a decreased number of T helpers and T regulatory cells expressing markers of early and late positive activation, limiting the development of both autoimmune reactions and the development of stress-induced neuroinflammation. No significant differences were found between the indices control group and comparison group, thus indicating that the severity of stress-induced neuroimmune reactions leveled out over time. Hematopoiesis induction by stress mediators and indirect neuroimmune-mediated changes in the quantitative profile of lymphocyte subpopulations seem to be a consequence of a complex multi-level neuropsychodynamic process of the central nervous system associated with clinical forms of adaptation disorders.