Korean Researchers First in the World to Identify Weakened Innate Immunity in 'Severe' COVID-19 Patients

[Asia Economy Reporter Kim Bong-su] Domestic researchers have, for the first time in the world, identified the differences between people infected with COVID-19 who remain mild and those whose condition progresses to severe. They confirmed that while all infected patients exhibit weakened innate immune responses, this phenomenon persists for more than a week particularly in severe cases.

The Korea Advanced Institute of Science and Technology (KAIST) announced on the 10th that a research team led by Professor Shin Ui-cheol of the Graduate School of Medical Science and Engineering, in collaboration with Professors Kim Yeon-sook and Cheon Shin-hye of the Department of Infectious Diseases at Chungnam National University Hospital, confirmed that COVID-19 patients have weakened antiviral functions of natural killer cells, especially in severe patients where this weakening lasts for over a week. This is the first identification of functional abnormalities in natural killer cells, which play a key role in antiviral innate immune responses, in severe COVID-19 patients.

When the human body is infected by a virus, an innate immune response is initially triggered, with natural killer cells being the primary cells responsible for antiviral innate immunity. Most natural killer cells are cytotoxic natural killer cells that directly kill virus-infected cells. Although previous reports indicated a decrease in the number or function of these cytotoxic natural killer cells in COVID-19 patients, the specific changes in natural killer cells or the mechanisms behind their functional decline had not been elucidated.

The research team conducted a longitudinal study tracking Korean COVID-19 patients from early diagnosis through recovery, revealing for the first time the changes occurring in natural killer cells during the progression of COVID-19 infection. They also identified differences in the characteristics and functions of natural killer cells between severe and mild patients. Notably, this study employed cutting-edge immunological research techniques alongside gene expression analysis to analyze and clarify the changes in natural killer cells in COVID-19 patients from multiple perspectives.

The team discovered atypical natural killer cells uniquely present in COVID-19 patients, unlike in healthy individuals or influenza patients, and confirmed that these atypical natural killer cells exhibit reduced cytotoxic function compared to typical natural killer cells.

These atypical natural killer cells rapidly increase in the early stages of the disease in COVID-19 patients regardless of disease severity, leading to weakened innate immune responses. Tracking the characteristics of natural killer cells throughout the disease course in COVID-19 patients revealed that the increase of these atypical natural killer cells persists longer in severe COVID-19 patients, which is associated with impaired innate immune responses.

The study results were published in the international journal The Journal of Allergy and Clinical Immunology.

Dr. Im Ga-ram, a researcher at KAIST, stated, "We discovered a characteristic increase of atypical natural killer cells in COVID-19 infection," adding, "These changes in natural killer cells, not observed in other respiratory viral infections, will help understand the clinical features of COVID-19 and provide clinical evidence for early proactive treatment in severe patients."

Professor Kim Yeon-sook of Chungnam National University also said, "This study is the first in the world to analyze and identify changes and characteristics of natural killer cells from the early disease stage to recovery in COVID-19 patients," and added, "It is a meaningful study as it reveals, for the first time, the mechanism of innate immune response impairment in COVID-19 patients."

This content was produced with the assistance of AI translation services.