Tonsils and adenoids are involved in the activation of memory immune cells after corona infection and vaccination

Professor Kim Hyun-jik, Department of Otolaryngology, Seoul National University Hospital (Photo = Provided by Seoul National University Hospital)

(Health Korea News / Lee Chang-yong) A study found that the tonsils and adenoids in the human upper respiratory tract activate the virus’s ‘memory immune cells (memory T and B cells)’ after COVID-19 infection or vaccination, thereby reducing the severity of the infection. The tonsils and adenoids were previously considered to be organs that could be removed without major problems when necessary, but now that they have been confirmed to increase defense against the virus, it is pointed out that caution is needed in removing them.

The results of a follow-up study that elucidated the impact of immune responses in adenoids on the course of COVID-19 disease were also published, and are expected to serve as basic data for establishing strategies for developing mucosal immune vaccines and treatments.

A research team led by Professors Kim Hyeon-jik (Otorhinolaryngology) and Park Wan-beom (Infectious Diseases) at Seoul National University Hospital announced on the 5th that they analyzed the immune response in the adenoids of COVID-19 patients during the Omicron mutation epidemic period (May 2022 to January 2023) and identified a correlation with clinical outcomes.

코로나19 감염 환자의 아데노이드에서 활성화되는 선천성 면역 인자 (가로축)과 임상 결과 (세로축)의 상관관계 (그림=서울대병원 제공)<br />” src=”<figcaption>Correlation between innate immune factors activated in the adenoids of patients with COVID-19 infection (horizontal axis) and clinical outcomes (vertical axis) (Figure = provided by Seoul National University Hospital)</figcaption></figure>
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<p>The research team collected nasopharyngeal samples from patients with mild and severe COVID-19 and healthy controls. Using RNA sequencing and molecular biology techniques, they analyzed the impact of interferon and interferon-stimulated genes (ISGs) expression in the nasopharynx on clinical outcomes in patients. Interferon is a key component of the innate immune response that is crucial for early immune defense. The degree of expression and the duration of the response can affect the course of the disease and the outcome of treatment.</p>
<p>The study results showed that mild COVID-19 patients had increased expression of interferon and interferon-inducible genes (ISGs) in their adenoids, which was closely related to positive clinical outcomes. The stronger the interferon response, the more the virus spread was suppressed and the shorter the recovery time. Although the interferon response was also observed in the adenoids of severe patients, the expression level was lower than that of mild patients. Through this, the research team clarified that the strength and timing of the immune response affect the severity of the disease.</p>
<p>The research team also confirmed that activated macrophages (M1), dendritic cells (DCs), and CD4+ memory T cells in the adenoids of COVID-19 patients play a major role in interferon activation.</p>
<p>This study suggests that the innate immune response and memory immune cell activation in the adenoids play an important role in preventing progression to severe disease after viral infection. </p>
<p>Professor Kim Hyun-jik said, “This study will serve as important research evidence for the development of new vaccines and treatments to be delivered to the upper respiratory tract to suppress COVID-19 infection.” He also said, “People without tonsils and adenoids are more likely to develop severe COVID-19 and cannot function as an active space for virus memory immune cells, so tonsil and adenoid removal surgery should be carefully decided after considering snoring and sleep apnea symptoms.”</p>
<p>This study was published online in August in the international academic journal ‘Cellular and Molecular Life Science’.</p>
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코로나19 환자의 아데노이드에서 인터페론 면역 반응 유도 세포의 규명 (그림=서울대병원 제공)<br />” src=”<figcaption>Identification of cells that induce interferon immune response in adenoids of COVID-19 patients (Image = Provided by Seoul National University Hospital)</figcaption></figure>
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<p>Meanwhile, this study is a follow-up study on the activation of tonsil and adenoid memory immune cells conducted by the La Jolla Institute for Immunology in the United States in 2022. Professor Kim Hyeon-jik participated as a co-researcher in the study by the La Jolla Institute for Immunology in the United States.</p>
<p>The tonsils and adenoids are the first target tissues for viruses to infect the human body. They are widely recognized as frequent infection-causing organs and as a cause of snoring and sleep apnea by narrowing the upper airway when they grow large. Thousands of tonsillectomies and adenoidectomies are performed in Korea each year. </p>
<p>However, since the histological morphology of the tonsils and adenoids is similar to that of the lymph nodes where memory immune cells are produced after vaccination, it was necessary to understand them as immune organs that help the body rather than targets for removal.</p>
<p>Accordingly, the La Jolla Immunological Research Institute conducted a study on memory immune cells activated in adult tonsils and adenoids. As a result, it was confirmed that acquired immune cells were activated in adenoids after COVID-19 vaccination. After vaccination, memory immune cells existed in adenoids for more than a year, and immune function was maintained longer than in the blood. This study was published in the international academic journal ‘Nature’.</p>
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