Секреторный иммуноглобулин А респираторной системы и COVID-19

In condition of COVID-19 the main focus goes on assessing the overall immune response; the role of mucosal immunity to this disease has not been studied sufficiently. Objective: To analyze published data about secretory IgA, as a significant indicator of the mucosal immune response of the respiratory tract in the context of the COVID-19 pandemic. Materials and methods: Articles were identified via PubMed bibliographic database. The timespan of research is two years (2020, 2021). Results: The search process identified 54 literature articles. There is evidence that secretory IgA (sIgA) is the main antibody isotype of the mucosal immune system. It is produced in quantities significantly higher than those of all other isotypes of immunoglobulins combined. sIgA antibodies are effective against various types of pathogens, including the SARS-CoV-2 virus, due to mechanisms such as neutralization, suppression of adhesion to the mucosal surface and invasion of epithelial cells, agglutination and facilitating the removal of pathogenic microorganisms in the mucosal secretions. Intracellular mechanisms for inhibiting viral replication are also described. Virus-specific IgA antibodies in the blood serum are detected in patients with COVID-19 at earlier time (as early as two days after the appearance of the first symptoms), compared with IgM or IgG class antibodies (after 5 days). The possibility of intranasal immunization as an effective mean of forming mainly sIgA in the upper and lower respiratory tract is considered. Conclusion: The current information on the local immune response of the respiratory mucosa is important for understanding the pathophysiological mechanisms of the disease, diagnosis, and development of new methods of treatment and prevention of COVID-19.