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Cross-reactive tissue-resident CD8+ T cells may provide first line of defence against SARS-CoV-2


Cross-reactive CD4+ T cells, likely induced by common cold coronavirus infections, are detected in 20–50% of peripheral blood samples from SARS-CoV-2 unexposed individuals. However, cross-reactive CD8+ T cells are rarely detected in these samples. To study whether this may be because CD8+ memory T cells are mostly located in tissues, Niessl at al. examined peripheral blood and tonsillar tissue samples from pre-2019. Indeed, they detected SARS-CoV-2 reactive CD8+ memory T cells in 32% of tissue samples. Cross-reactive CD4+ cells were detected at similar levels in blood and tissue, whereas cross-reactive memory CD8+ T cells were largely absent in matched blood samples. Tissue-resident cross-reactive CD8+ memory T cells displayed markers of follicular homing and tissue residency, and the authors speculate that these may enable rapid sentinel immune responses to SARS-CoV-2.


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Correspondence to Alexandra Flemming.

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Flemming, A. Cross-reactive tissue-resident CD8+ T cells may provide first line of defence against SARS-CoV-2. Nat Rev Immunol 21, 693 (2021).

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