Highly functional virus-specific cellular immune response in asymptomatic SARS-CoV-2 infection

N Le Bert, HE Clapham, AT Tan, WN Chia… - Journal of Experimental …, 2021 - rupress.org
N Le Bert, HE Clapham, AT Tan, WN Chia, CYL Tham, JM Lim, K Kunasegaran, LWL Tan…
Journal of Experimental Medicine, 2021rupress.org
The efficacy of virus-specific T cells in clearing pathogens involves a fine balance between
antiviral and inflammatory features. SARS-CoV-2–specific T cells in individuals who clear
SARS-CoV-2 without symptoms could reveal nonpathological yet protective characteristics.
We longitudinally studied SARS-CoV-2–specific T cells in a cohort of asymptomatic (n= 85)
and symptomatic (n= 75) COVID-19 patients after seroconversion. We quantified T cells
reactive to structural proteins (M, NP, and Spike) using ELISpot and cytokine secretion in …
The efficacy of virus-specific T cells in clearing pathogens involves a fine balance between antiviral and inflammatory features. SARS-CoV-2–specific T cells in individuals who clear SARS-CoV-2 without symptoms could reveal nonpathological yet protective characteristics. We longitudinally studied SARS-CoV-2–specific T cells in a cohort of asymptomatic (n = 85) and symptomatic (n = 75) COVID-19 patients after seroconversion. We quantified T cells reactive to structural proteins (M, NP, and Spike) using ELISpot and cytokine secretion in whole blood. Frequencies of SARS-CoV-2–specific T cells were similar between asymptomatic and symptomatic individuals, but the former showed an increased IFN-γ and IL-2 production. This was associated with a proportional secretion of IL-10 and proinflammatory cytokines (IL-6, TNF-α, and IL-1β) only in asymptomatic infection, while a disproportionate secretion of inflammatory cytokines was triggered by SARS-CoV-2–specific T cell activation in symptomatic individuals. Thus, asymptomatic SARS-CoV-2–infected individuals are not characterized by weak antiviral immunity; on the contrary, they mount a highly functional virus-specific cellular immune response.
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