Cytotoxic lymphocytes such as cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells are necessary for the control of viral infection, and the functional exhaustion of cytotoxic lymphocytes is correlated with disease progression.
We [demonstrate here] that the total number of NK and CD8+ T-cells was decreased markedly in patients with SARS-CoV-2 infection. The function of NK and CD8+ T-cells was exhausted with the increased expression of NKG2A in COVID-19 patients. Importantly, in patients convalescing after therapy, the number of NK and CD8+ T-cells was restored with reduced expression of NKG2A. These results suggest that the functional exhaustion of cytotoxic lymphocytes is associated with SRAS-CoV-2 infection.
T-cell and CD8+ T-cell counts were decreased significantly in [mild and severe COVID-19] patients compared with those in healthy controls. The number of T-cells and CD8+ T-cells was significantly lower in severe patients than that in mild cases. The counts of NK cells were reduced remarkably in severe patients compared with those in mild cases and healthy controls.
SOURCE: Cell & Molecular Immunology