Fig. 4

ISG15 down-regulates the expression of glycosylated PD-L1. A Western blot analysis of the protein level of PD-L1 in control or Lv-ISG15 or Sh-ISG15 A549, H1299 and LLC cells. B After 5 ng/ml IFN-γ treatment of cells in the control group or Lv-ISG15 group for 12 h, mRNA levels of ISG15 were measured by quantitative qRT-PCR and protein expression levels of PD-L1 were measured by Western blot. C Cellular immunofluorescence staining was used to observe the expression of PD-L1 in Sh-ISG15 and Lv-ISG15 or the control A549/H1299 cells. D The plasma membrane PD-L1 in control or sh-ISG15 A549/H1299 cells was detected by flow cytometry. The data are shown as the mean ± SD. Ns means no significance. *P < 0.05, **P < 0.01, ***P < 0.001