fig1

Figure 1. Mechanism of PD-1/PD-L1 inhibitors (ICIs) in the TME. APCs present tumor antigens to T cells through MHC-TCR interaction, accompanied by co-stimulatory signals (CD80/CD86) and cytokines that promote T cell activation. Within the TME, tumor cells overexpress PD-L1, which binds to PD-1/CD279 on activated T cells, suppressing their cytotoxic activity. PD-1/PD-L1 inhibitors block this inhibitory interaction, thereby restoring T cell activity, TIL function, and reactivating antitumor immune surveillance. Created in BioRender. Wang, L. (2025) https://BioRender.com/x410r92. PD-1: Programmed cell death protein-1; PD-L1: programmed death-ligand 1; ICIs: immune checkpoint inhibitors; TME: tumor microenvironment; APCs: antigen-presenting cells; MHC: major histocompatibility complex; TCR: T cell antigen receptor; TIL: tumor-infiltrating lymphocyte; TGF-β: transforming growth factor-β; IL-10: interleukin-10.