Used in immunological research to study T-cell activation and signaling pathways. Serves as a capture antigen in ELISA and other immunoassays for detecting anti-CD3 antibodies or evaluating T-cell receptor interactions. Employed in protein-protein interaction studies due to the His tag, enabling easy purification and immobilization on nickel-coated surfaces. Commonly used in the development and testing of therapeutic antibodies targeting the CD3 complex in autoimmune diseases and cancer immunotherapy. Supports in vitro T-cell stimulation when immobilized on solid surfaces.