PD-1 is an immunosuppressive receptor expressed on activated T cells and B cells, playing a crucial role in regulating immune responses to tumor antibodies and self-antigens. The interaction between PD-1 on neighboring cells and its ligands PD-L1 or PD-L2 inhibits the transduction of the TCR signaling pathway and TCR-mediated cellular proliferation, transcription activation, and cytokine production. Therapeutic antibodies and Fc fusion proteins that block the PD-1/PD-L1 interaction have shown promising prospects in clinical trials for treating various cancers.CTLA-4, also known as CD152, is an immunosuppressive receptor expressed constitutively on regulatory T cells (Treg), playing a key role in regulating immune responses. When CTLA4 is upregulated on the surface of T cells, it binds with higher affinity to CD80 (B7-1) or CD86 (B7-2) than the CD28 positive co-stimulatory signal, thereby inducing T cells unresponsiveness. Antibodies and Fc fusion proteins that block the CTLA4/CD80 and CD86 interaction have shown good prospects in clinical trials for treating various cancers.Clinical data has demonstrated that the combined use of CTLA-4 and PD-1 antibodies or the use of CTLA-4/PD-1 bispecific antibodies results in superior treatment outcomes compared to using single CTLA-4 or PD-1 antibodies.The CTLA4 PD-1 Reporter Cell Line is a stable cell line expressing luciferase reporter genes for CTLA-4 and PD-1. Co-culturing it with CD80 PDL1 aAPC CHO-K1 Cell Line results in the inhibition of TCR downstream signaling by blocking the binding of CTLA-4 to CD28 and PD-1 to PD-L1. Upon addition of CTLA-4, PD-1, or CTLA-4/PD-1 bispecific antibodies, the blockage of CTLA-4/PD-1 is lifted, and the TCR signaling is restored, with Luciferase readings reflecting the activation of the signaling pathway. This cell line can be used for evaluating the in vitro effects of CTLA-4/PD-1-related drugs.
