Effective Natural Killer Cell Degranulation Is an Essential Key in COVID-19 Evolution

Area of Science:

• Immunology
• Infectious Diseases
• Cellular Biology

Background:

• Natural killer (NK) cell degranulation is vital for innate immunity against intracellular infections and influences disease progression.
• Understanding NK cell function in COVID-19 is critical for predicting disease severity and patient outcomes.

Purpose of the Study:

• To investigate NK cell degranulation and innate immune profiles in COVID-19 patients.
• To determine the association between NK cell functionality and COVID-19 severity.

Main Methods:

• A prospective observational study involving 99 COVID-19 patients.
• Analysis of innate immune cell subpopulations and their functionalities.
• Grouping patients based on hospital requirements and disease severity.

Main Results:

• Significant differences in innate immune cell profiles and functions were observed between healthy controls and severe COVID-19 patients.
• Severe COVID-19 was associated with increased CD56dim NK cells, decreased MAIT cells, and reduced NK degranulation rates.
• Higher NK degranulation rates were found in non-severe patients and healthy controls compared to severe patients.
• A higher granzyme A/granzyme B ratio was noted in milder disease forms.
• Multivariate analysis identified NK cell degranulation capacity as a protective factor (OR: 0.86) and persistent NKG2D expression on NKT cells as a risk factor (OR: 3.81) for severe disease.

Conclusions:

• Impaired NK cell degranulation functionality is linked to increased severity in COVID-19 patients.
• Early assessment of NK cell degranulation capacity may serve as a valuable tool for predicting patient prognosis and identifying those likely to experience a better disease evolution.