Used in immunological research to study T-cell activation and immune regulation. Serves as a binding partner in checkpoint pathway assays, helping evaluate potential immunotherapies for cancer and autoimmune diseases. The His Tag allows for easy purification and detection in protein interaction studies. Commonly used in ELISA, surface plasmon resonance, and flow cytometry to measure receptor-ligand binding. Supports development of monoclonal antibodies and bi-specific molecules targeting the HHLA2 pathway.