Enhanced expression of immunostimulatory molecules on CpG-Stat3 siRNA–treated AML cells in vivo. (A-B) AML-bearing C57BL/6 mice were treated with CpG-Luc siRNA or CpG-Stat3 siRNA as in Figure 2. The surface expression of MHC class II and (A) costimulatory molecules CD40, CD80, and CD86 or (B) coinhibitory PD-L1 molecules on splenic AML cells was assessed by flow cytometry. Shown are representative histogram overlays and bar graphs summarizing mean fluorescence intensity (MFI) from each group of mice (n = 6); mean ± standard deviation (SD). (C-D) Levels of different cytokines in blood plasma of mice treated as in (A) were quantified by using Luminex assays. Shown are means ± SEM (n = 6). Statistically significant P values are indicated by asterisks: ***P < .001; **P < .01; *P < .05. (E) In vivo pretreated splenic AML cells were cocultured in vitro with autologous T cells at a ratio of 1:1 for 3 days. T-cell proliferation was assessed by using carboxyfluorescein succinimidyl ester (CFSE) dilution assay. Shown are results representative for 3 independent experiments.