The effects of treatment with an anti-PD-L1 monoclonal antibody on NK cells. The PD-L1 antibody was used as follows: G1–3 (1, 2.5, or 5 µg/mL for 72 hours), G4–6 (1, 2.5, or 5 µg/mL for 48 hours), G7–9 (1, 2.5, or 5 µg/mL for 24 hours). The cells were then respectively co-cultured with H1975 cells at an E:T ratio of 10–20:1 and the extent of lysis was estimated by the LDH assay (A). The cytotoxicity of the combination treatment compared with treatment with NK cells alone (B). The phenotypic signatures of NK cells treated with the PD-L1 antibody for 24 hours at an E:T ratio of 20:1 against H1975 (analyzed by flow cytometry). PD-L1 (C), CD107a (D), NKG2D (E). PD-1, programmed cell death protein-1; NK, natural killer; LDH, lactate dehydrogenase; NKG2D, natural killer group 2D.