Used in immunological research to study T-cell activation and co-stimulatory signaling pathways. Facilitates the development of assays for measuring protein-protein interactions involving ICOS and its ligand ICOS-L. Supports the screening and characterization of therapeutic antibodies or inhibitors targeting the ICOS pathway, which is relevant in autoimmune diseases, cancer immunotherapy, and inflammatory conditions. The His tag allows for easy purification and detection in recombinant systems, enabling consistent experimental results in ELISA, surface plasmon resonance, and cell-based assays.