Used in research and development for treating autoimmune diseases such as systemic lupus erythematosus and type 1 diabetes by targeting the interleukin-21 (IL-21) pathway. It helps modulate immune responses by neutralizing IL-21 activity, which plays a role in B and T cell activation. This antibody serves as a reference standard in bioassays to evaluate the potency and efficacy of anti-IL-21 therapeutics during drug development. It is also employed in preclinical studies to understand the role of IL-21 in immune regulation and inflammation.