PD-1 is an immunosuppressive receptor expressed on activated T cells and B cells, playing a critical role in regulating immune responses to tumor antibodies and self-antigens. Interaction between PD-1 on neighboring cells and its ligands PD-L1 or PD-L2 inhibits TCR signaling pathway transduction, as well as TCR-mediated cell proliferation, transcription activation, and cytokine production. Therapeutic antibodies and Fc fusion proteins blocking PD-1/PD-L1 interactions have shown promising application prospects in clinical trials for various cancers. Current methods for evaluating the activity of anti-PD-1 or anti-PD-L1 biological products rely on measuring primary human T cell and functional endpoints such as cell proliferation, cell surface marker expression, interferon-gamma (IFNγ), and interleukin-2 (IL-2) production. Due to reliance on donor primary cells, complex experimental protocols, and substandard reagents, these assays are both labor-intensive and prone to variability. Therefore, these assay methods are challenging to establish in a quality-controlled drug development environment.The Mouse_PD-1 Reporter Jurkat Cell Line is a reporter gene cell line stably expressing the Mouse_PD-1 gene and Luciferase reporter gene. Paired with the Mouse PDL1 aAPC CHO-K1 Cell Line, which stably expresses mouse PD-L1 and a cell surface protein that activates endogenous TCR in an antigen-independent manner. When both cell lines are co-cultured, the interaction between PD-1/PD-L1 inhibits TCR signaling pathway transduction and transcription factor-mediated luciferase expression. Addition of a blocking antibody against PD-1/PD-L1 reverses this inhibition, leading to TCR signaling pathway transduction and transcription factor-mediated luciferase expression, which can be used to assess the efficacy and stability of blocking antibodies against PD-1/PD-L1 interactions and other biological products.
