Recombinant Human PD-1/PDCD1 Protein (C-His)

Measured by functional ELISA. Immobilized recombinant human PD-1 binds a reference anti-human PD-1 monoclonal antibody with an EC50 in the range of 20–60 ng/mL. Binding of PD-L1 is fully blocked by checkpoint inhibitor antibodies.

Programmed cell death protein 1 (PD-1), also known as PDCD1, is a type I transmembrane receptor of the CD28 costimulatory family and one of the central immune checkpoint regulators. PD-1 is induced on activated T cells, B cells, NK cells and monocytes, and delivers inhibitory signals through its cytoplasmic ITIM and ITSM motifs after engagement by its two ligands, PD-L1 (B7-H1/CD274) and PD-L2 (B7-DC/PDCD1LG2). By attenuating TCR/CD28 signaling — most notably the PI3K/AKT pathway — the PD-1/PD-L1 axis restrains peripheral immune activation and maintains self-tolerance, while tumors exploit it as a dominant mechanism of immune escape. Blockade of this axis with antibodies such as pembrolizumab, nivolumab and cemiplimab has transformed the treatment of melanoma, NSCLC and many other malignancies, making PD-1 one of the most intensively studied drug targets in immuno-oncology. High-purity recombinant human PD-1 is an essential reagent for therapeutic antibody screening, blocking and binding assays, ELISA pair development, and label-free affinity measurement by SPR/BLI.