Dynamics of specific humoral response in COVID-19 patients

ABSTRACT

Introduction. The pandemic caused by the SARS-CoV-2 virus is an important medical and social problem. It remains unclear the stability of the developed humoral immunity against the SARS-CoV-2 virus, the average duration of preservation of the titer of specific antibodies. The need to identify humoral mechanisms of immune defense in patients with COVID-19 determined the purpose of this study. The aim of the study – to evaluate the dynamics of changes in the content of specific IgG antibodies against various antigens of the SARS-CoV-2 virus and B-lymphocyte subpopulations throughout the year in people who have had COVID-19. Material and methods. The study included 90 patients who had undergone COVID-19 in various forms, subsequently divided into 2 groups persons with asymptomatic and mild course (57 patients) and with moderate or severe course of the disease (33 patients). The dynamics of the concentration of specific antibodies to the SARS-CoV-2 virus was evaluated by enzyme immunoassay every 3 months for a year. The content of the total pool B-lymphocytes (naive B-lymphocytes, memory B-cells, regulatory B-lymphocytes) and various subpopulations was evaluated by flow cytofluorimetry. Results. When assessing the dynamics of IgG to the S-protein of the SARS-CoV-2 virus, their preservation was noted by the 12th month after recovery. In patients with severe and moderate COVID-19 forms, these indicators are significantly higher. More severe forms of COVID-19 are accompanied by significantly higher content level of memory B cells throughout the observation period. Conclusion. Moderate and severe forms of COVID-19 induce more persistent postinfectious humoral immunity, provided by an increase in memory B cells in comparison with lighter forms.