Figure 2.

IBI323 activates T cells by blocking the interaction of PD-L1/PD-1 and LAG-3/MHC-II. (a) IBI323 completely blocks the interaction of PD-1 with PD-L1 expressed on CHO-S cells. Cell-based blocking assay was conducted for IBI323, Bi127, and IgG using PD-L1-expressing cell line and PD-1-Fc protein. After incubation and washing, PD-1-Fc was detected by anti-human Fc-PE secondary antibody. (b) IBI323 completely blocks the interaction of CD80 with PD-L1 expressed on CHO-S cells. (c) IBI323 completely blocks the interaction of LAG-3 with MHC-II expressing CHO-S cells. (d) IBI323 blocks PD-1/PD-L1 interaction and promotes T-cell activation in a PD-L1 blockade reporter assay. Jurkat T cells engineered to express human PD-1 with a luciferase reporter driven by an NFAT response element were co-cultured with CHO-K1 cells expressing PD-L1 and an artificial T cell receptor activator. Serially diluted IBI323, IBI110, Bi-127, or IgG1 control was added and luminescent signal was measured after 6 h. (e) IBI323 blocks LAG-3/MHC-II interaction and promotes T-cell activation in a blockade reporter assay. Jurkat T cells engineered to express LAG-3 with a luciferase reporter driven by an NFAT response element were co-cultured with APCs expressing MHC-II in the presence of HA-peptide. Serially diluted IBI323, IBI110, Bi-127, or IgG1 was added and luminescent signal was measured after 6 h. All the data are representative of at least three independent experiments