Used in immunological research to study antibody-dependent immune responses. Plays a key role in analyzing interactions between immunoglobulins and immune cells, particularly in the context of autoimmune diseases, infectious diseases, and therapeutic antibody development. The His tag enables efficient purification and detection, making it valuable for in vitro binding assays, receptor-ligand studies, and high-throughput screening of antibody candidates. Commonly applied in drug discovery to assess antibody effector functions such as phagocytosis and cytokine release.