Immune dysregulation in long covid may contribute to the development of neurological disorders through the effects of cytokines

Aim of the study: to investigate the role of proinflammatory markers and some immune cells in neural and cognitive disorders in long COVID patients. Materials and methods. The study included 81 patients diagnosed with long COVID, the presence of which was determined by the persistence of a complex of multidirectional symptoms for more than 12 weeks that developed during or after COVID-19. Flow cytometry was used to assess lymphocyte subsets. The main lymphocyte subpopulations were analyzed: T cells, cytotoxic T cells, B cells, NK and NKT cells in blood plasma via multiplex xMAP analysis. Also concentrations of GM-CSF, IL-1, IL-2, IL-4, IL-5, IL-6, IL-8, IL-12, IL-13, IL-17, MCP-1, MIP-1b, TNF were measured. The content of proinflammatory cytokines and some immune system cells was characterized in respondents with long COVID. A comparative analysis of data was conducted with individuals without a history of COVID-19, as well as between patients with different numbers of SARS-CoV-2 cases. Results and discussion. The study identified characteristic features of long COVID that affect both the nervous and immune systems. Analysis of the blood cells revealed absolute and relative lymphopenia due to a decrease in NK cells. We also noticed an increased number of NKT cells in patients who suffered multiple COVID-19, when compared to those who only were infected with SARS-CoV-2 once. Cytokine analysis revealed increase in concentrations of IL-5, IL-8, IL-13, IL-17 and CCL2/MCP1 in blood plasma of long COVID patients. Conclusion. The data provides additional support to the theory of immune dysregulation in neurological symptoms of long COVID.