Used in immunological research to study immune checkpoint pathways, particularly in modulating T-cell and NK cell activity. Helps in the development of therapeutic antibodies and biologics targeting immune regulation. Commonly employed in protein-protein interaction studies, ELISA, flow cytometry, and binding assays to evaluate ligand interactions such as HLA class I molecules. Supports drug discovery in oncology, autoimmune diseases, and transplantation medicine by serving as a detection or blocking reagent in functional assays.