Figure 5.

Inhibition of PD-1 increases killing of NPC cells by NK after radiation. NPC and NK cells were irradiated with 2 Gy. 24 h later, target cells were labeled with calcein, plated in a 96-well plate and incubated with NK cells for 4 h at an E:T ratio of 6:1. Lysis of target cells was determined by measurement of calcein in collected supernatants by an ELISA reader. Data are presented as means ± S.E.M. Asterisks indicate statistically significant differences between all cell lines in one ratio-group (two-way ANOVA; * p < 0.05; ** p < 0.01; *** p < 0.001, n.s.: not significant).