MKN45 and A549 cells were pretreated with IFN-γ (500 U/mL) for 48 h, washed and cocultured with human Jurkat T cells, either with cell contact or in transwell coculture, in the presence of PHA (1 μg/mL) for 48 h. IL-2 production was detected by ELISA. (A) The expression of PD-1 in Jurkat T cells with or without PHA stimulation by flow cytometry. (B) The relative mRNA expression of PD-L1 in cancer cell lines, with or without IFN-γ stimulation, detected by qPCR. IFN-γ (−) as the calibrator sample. (C, F) Inhibition of IL-2 production by Jurkat T cells in coculture with MKN45 (C) and A549 cells (F) at different E:T proportions. (D, G) Enhanced IL-2 production in transwell cocultures in MKN45 cells (D) and A549 cells (G). (E, H) Restoration of IL-2 production by addition of BsAb to Jurkat T cell-contact cocultures with MKN45 cells (E) and A549 cells (H). The assays were repeated three times and each sample has 3 holes, the results were shown as mean ± SD. **: P < 0.01.