Programmed cell death protein 1–Programmed death-ligand 1 interface (PD-1–PD-L1 interface)

The PD-1–PD-L1 interface is a critical immune checkpoint that regulates the balance between immune activation and self-tolerance. Programmed cell death protein 1 (PD-1) is an inhibitory receptor primarily expressed on the surface of activated T cells, B cells, and myeloid cells, while its ligand, Programmed death-ligand 1 (PD-L1), is expressed on antigen-presenting cells and frequently overexpressed by various tumor cells. When PD-L1 binds to PD-1, it initiates inhibitory signaling through the recruitment of phosphatases like SHP-2, which dephosphorylate T-cell receptor signaling components, leading to suppressed T-cell proliferation, reduced cytokine production, and T-cell exhaustion. Many cancers exploit this pathway to evade immune surveillance and promote tumor progression. Therapeutic targeting of this interface with monoclonal antibodies (checkpoint inhibitors) prevents the PD-1/PD-L1 interaction, effectively "releasing the brakes" on the immune system and enabling T cells to recognize and eliminate malignant cells. This strategy has revolutionized oncology, providing durable clinical responses across a wide range of solid and hematological malignancies.

Other names

PD-1/PD-L1 axisPD-1/PD-L1 pathwayPD-1/PD-L1 signaling axisPD-1/PD-L1 immune checkpointCD279/CD274 interface

Immune checkpoint inhibition by blocking the protein-protein interaction between PD-1 and PD-L1 to restore T-cell mediated anti-tumor activity.