Fig. 3　Nivolumab enhances the adjuvant effect of NKT cells on NK cells. (A, B) Purified NKT cells treated with nivolumab or isotype hIgG4 were co-cultured with K562 cells in the top compartments of transwells, while NK cells were co-cultured with CTV-labeled K562 cells (E/T ratio of 1:1) or A549 cells (E/T ratio of 2:1) in the bottom compartments of the transwells. The cells in the bottom compartments were harvested after 4 h of culture, and stained with annexinV and PI to assess K562 or A549 cell-specific apoptosis. (A) Data for CTV⁺ K562 cells and CTV⁺ A549 cells. (B) NK cell cytotoxicity against K562 or A549 cells calculated. Bars and error bars indicate the mean and SD of biological triplicate, respectively (n = 3) . The data are representative of the results from two independent experiments. P-values were calculated by an unpaired t-test. **P<0.01, ***P<0.001, n.s.: not significant.