Infection with the coronavirus that causes severe acute respiratory syndrome (SARS-CoV-2) triggers adaptive cellular immune responses. Peripheral blood is examined in numerous SARS-CoV-2 research to investigate immunological responses. A recent study published in the Nature Portfolio Journal looks at children’s tonsils, peripheral blood, and adenoids to better understand local and systemic immune responses to SARS-CoV-2. While the research paper is peer-reviewed, a preprint version is available at Research Square.
Adaptive immune responses at the local level
Infection and replication of SARS-CoV-2 occur in the upper respiratory tract. Tonsils and adenoids, located in the nose and throat, are the lymph glands nearest to the virus’s entry point. T- and B-cell responses to SARS-CoV-2 antigens within the upper respiratory tract are formed here. In youngsters, tonsillectomy but also adenoidectomy are common procedures. Local adaptive immune responses can be studied using tonsils and adenoids.
The lymph glands’ cellular connections
The lymph glands are where lymphatic T and B lymphocytes are activated and matured. To facilitate immunoglobulin gene class switching, T follicular helper cells (Tfh) and B cells collaborate. This encourages the establishment of germinal centres (GCs), which allow B cells to mature and produce antibodies plus memory B cells.
According to studies, serum antibody levels in individuals with deadly coronavirus disease 2019 (COVID-19) remain short-lived due to losing GCs from thoracic lymph nodes. GCs, on the other hand, has been proven to provide long-lasting B cell protection in several investigations. According to some investigations, the cells have also been found in the lymph glands and lung tissues of organ donors.
The study’s limitations
The timing of SARS-CoV-2 infection was unknown to the researchers in this investigation. Many participants were unaware that they have COVID-19. The researchers could not track the duration of immunological alterations due to a lack of longitudinal samples. It was impossible to distinguish antigen-specific T lymphocytes in lymph tissues. For sleep-disordered respiration, the COVID-19-convalescent kids had a tonsillectomy.
This study shows that SARS-CoV-2 immunity is durable and localized. In contrast, weeks to months following the acute infection, COVID-19-convalescent kids displayed powerful, lymph-tissue-specific adaptive immune responses.