Fig. 2.

Type I interferon induction by GMCI and stimulation of PD-L1 expression. (A) IFN-β released from infected CT-2ALuc and GL261Luc2 tumor cells was detected 4 days after GMCI treatment by ELISA assay. (B) GL261Luc2 and CT-2ALuc cells were treated with 1000 U/mL IFN-α and IFN-β for 4 days followed by flow cytometry for cell surface PD-L1 detection. (C) Representative immunofluorescence images of PD-L1 expression (red) in GL261Luc2 cells after treatment with IFN decoy antibody MAR1-5A3. Ten micrograms per milliliter of MAR1-5A3 antibody and 1000 U/mL or 10 μg/mL/day GCV were added to the tumor cells 3 h after treatment with 10 vp/μL AdV-tk. Scale bar: 50 µm. One-way ANOVA was used to determine statistical significance (***P ≤ 0.001, **P ≤ 0.01).