Indexes of innate and adaptive immunity in the patients with SARS-CoV-2 infection

The main pathogenetic mechanisms of the SARS-CoV-2 infection include imbalance of immune response and impaired cytokine regulation involving insufficient interferon synthesis at the onset of the disease, and subsequent hyperproduction of proinflammatory cytokines resulting in marked inflammation and damage of pulmonary parenchyma. Our objective was to perform monitoring of cytokine content, determination of antibodies, immune cells, and inflammatory biomarkers in the patients who had coronavirus infection caused by COVID-19, during the disease and over the convalescence period. The study included sixty patients at the age of 18 y.o. and older with severe and moderate course of disease caused by COVID-19. The diagnosis was verified in accordance with provisional instructional guidelines of the Ministry of Healthcare of the Russian Federation “Prevention, diagnosis and treatment of novel coronavirus infection (COVID-19)” version 11 (17.05.2021). The study involved analysis of medical documents, evaluation of differential white blood cell count, T cell subpopulations, C-reactive ptrotein (CRP) levels, interleukin-6 (IL-6), interferon gamma (IFNγ), tumor necrosis factor-alpha (TNFα), as well as IgM and IgG antibodies against SARS-CoV-2.
Statistical processing of data was performed by Statistica 13 program with critical significance level p < 0.05, correlations were analyzed using Spearman rank correlation coefficient, multidimensional correlation analysis with creation of pleiads, according to V.P. Terentyev’s method (1959), and Shapiro–Wilk testing for normality of data distributions. The sample size made it possible to evaluate the results at a significance of 95-99%. These studies have yielded the results concerning specific changes of the inflammatory biomarkers at different stages of disease, persistent changes in quantitative and qualitative characteristics of immune cells and cytokine levels, correlations between immunological indicators and severity of clinical course, and degree of damage to pulmonary parenchyma. During the period of significant clinical presentations, the patients with severe course of disease exhibited leukopenia with low proportion of lymphocytes, and maintenance of CRP and ESR at high levels for longer terms, including early recovery. Levels and changes in amounts of IgG and IgM antibodies to SАRS-CoV-2 varied in accordance with clinical severity and duration of convalescence period. During the recovery period, an imbalance of regulatory T cell subpopulations and low levels of IFNγ were observed. The stable impairment of structural and functional characteristics of immune cells and aberrant production of cytokines during the disease caused by SARS-CoV-2 may serve as a pre-requisite for monitoring immunological indices in search for personalized immunotropic therapy.