Figure 1.

Schematic representation of COVID-19 effects on NK cells. Acute SARS-CoV-2 infection affects the number of circulating NK cells and their phenotype. Indeed, due to the local and systemic inflammation, NK cells in COVID-19 patients are characterized by a signature attributable to cell activation and inflammation as well as to cell exhaustion and hyporesponsiveness. These alterations in NK cell phenotype determine an impairment of NK cell effector functions in terms of IFN-γ and TNF-α production, degranulation cytolytic potential and ability to control virus replication.