KLRK1 and COVID-19: In the context of COVID-19 treatment, the used of different lines such as NKG2D-ACE2 CAR-NK cells and ACE2 CAR-NK cells in combination with an IL-15 superagonist and Granulocyte-macrophage colony-stimulating factor (GM-CSF) neutralizing single-chain variable fragments are currently under investigation (NCT04324996) (79, 120).