Secretory immunoglobulin A of the respiratory system and COVID-19

ABSTRACT

The main focus in the course of COVID-19 goes on assessing the overall immune response. The role of mucosal immunity in this disease has not been studied sufficiently. The study aimed 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. Methods. Articles were identified via PubMed bibliographic database. The time-span of research was two years (2020, 2021). Results. The search identified 54 articles. There is evidence that secretory IgA (sIgA) is the main antibody isotype of the mucosal immunity. It is produced in quantities significantly higher than those of all other isotypes of immunoglobulins combined. sIgA antibodies are effective against various 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 with the mucosal secretions. Virus-specific IgA antibodies in the blood serum are detected in patients with COVID-19 as early as two days after the first symptoms, while IgM or IgG class antibodies appear only after 5 days. We accessed the efficacy of intranasal immunization as to induction of predominant production of sIgA in the upper and lower respiratory tract. 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.