Figure 4. Inhibition of thioredoxin-1 reduces NK cell surface thiol groups and reverses IL-15–mediated resistance to oxidative stress.

(A) MFI of maleimide staining on NK cells treated with PX-12 within IL-2– and IL-15–primed NK cell cultures (n = 6). (B) Percentage of increased ROS^hi NK cells after 10 μM H₂O₂ treatment compared with untreated NK cells in the presence or absence of PX-12 in IL-2 and IL-15 cultures (n = 6). (C) Relative increase in CellROX MFI in NK cell cocultures with or without PX-12 treatment, normalized to the control group without neutrophils (n = 6). (D) Relative fold-change of Ki-67 expression in NK cell cocultures with or without PX-12 treatment (n = 7). (E) Bright-field images of H1299 tumor spheres with green fluorescence–labeled NK cells. Images were acquired under a ×10 objective at 3 different time points. Scale bars: 400 mm. Vertical labels describe the pretreatment conditions of NK cells before coculture. (F) Percentage of infiltrating NK cells in tumor spheres with different NK cell pretreatments (n = 5). (G) Percentage of infiltrating NK cells in tumor spheres in FACS-sorted NK cells, based on maleimide staining (n = 4). All individual data points are connected for matching replicates. *P < 0.05, **P < 0.01, and ***P < 0.001, by repeated-measures 2-way ANOVA with Holm-Šidák’s multiple-comparisons test (A and B), Wilcoxon signed-rank test (for significance within IL-2 cultures) and Friedman’s test (for significance within IL-15 cultures) (C), Friedman’s test (D and F), and paired t test (G).