Programmed death-ligand 1 receptor (PD-1 (for the receptor), PD-L1 (for the ligand))

Programmed death-ligand 1 receptor (commonly discussed as the PD-1/PD-L1 interaction) describes the binding of the **Programmed death-1 (PD-1)** receptor, an immunoglobulin superfamily checkpoint protein expressed primarily on activated T cells, to its ligand **Programmed death-ligand 1 (PD-L1)**, a type I transmembrane glycoprotein expressed on various immune and tumor cells[1][3][4][5]. This interaction transmits inhibitory signals that dampen T cell activation, proliferation, and cytokine production, playing an essential role in immune homeostasis and the maintenance of self-tolerance[1][3][4]. In the tumor microenvironment, upregulation of PD-L1 allows cancer cells to evade immune recognition and attack, contributing to tumor progression[1][3][4][5]. Targeted therapies that block this interaction—immune checkpoint inhibitors—have become central in modern cancer immunotherapy, demonstrating significant clinical benefit in multiple tumor types but possessing unique safety challenges due to immune activation[4].

Other names

PD-1/PD-L1 interactionProgrammed death-1 (PD-1)Programmed death-ligand 1 (PD-L1)CD274 (for PD-L1)B7-H1 (for PD-L1)CD279 (for PD-1)Programmed cell death protein 1 (for PD-1)

Immune checkpoint blockade Inhibition of PD-1/PD-L1 binding, restoring T cell activation and cytotoxicity Enhanced anti-tumor immune response