Used in immunology research to study immune checkpoint pathways. Facilitates assays involving T-cell activation and inhibition by interacting with PD-1 receptors. Commonly employed in ELISA, surface plasmon resonance, and binding affinity studies to evaluate therapeutic antibodies or drug candidates targeting the PD-1/PD-L1 pathway. The His tag allows for easy purification and detection in recombinant protein workflows. Supports development of cancer immunotherapies and diagnostic tools.