Severe infection with severe acute respiratory syndrome coronavirus (SARS-CoV)-2 is characterized by massive cytokine release and T cell loss. The exaggerated host immune response, incapable of viral clearance, instead aggravates respiratory distress, as well as cardiac, and/or damage to other organs. The mortality pattern of SARS-CoV-2 infection, higher in older versus younger adults and almost absent in children, is possibly caused by the effects of age and pre-existing comorbidities on innate and adaptive immunity. Here, we speculate that the abnormal and excessive immune response to SARS-CoV-2 infection partly depends on T cell immunological memory, which is more pronounced in adults compared with children, and may significantly contribute to immunopathology and massive collateral damage in coronavirus disease 2019 (COVID-19) patients. Highlights T cell-mediated immunity is crucial for the effective clearance of severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infection. In severe and critical coronavirus disease 2019 (COVID-19) patients, peripheral blood T cells are significantly decreased and show a phenotype of hyperactivation/exhaustion relative to controls. Older age, characterized by high basal proinflammatory status coupled with a progressive inability to mount proper immune responses, is a major risk factor for severe and critical SARS-CoV-2 infection. Children are nearly always asymptomatic in SARS-CoV2 infection; this clinical observation may be linked to a higher proportion of naïve T cells in circulation than adults and, consequently, a presumed reduced susceptibility to hyperinflammatory collateral damage.
T Cells: Warriors of SARS-CoV-2 Infection
[Category] SARS,
[Article Type] Opinion
[Source] PMC
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