Used in immunological research to quantify C4b-binding protein alpha chain levels in biological samples such as plasma or serum. Helps in studying complement system regulation, particularly in autoimmune diseases like systemic lupus erythematosus (SLE), thrombotic disorders, and conditions involving dysregulation of the classical complement pathway. Enables researchers to assess C4BPA's role in inflammation, apoptosis, and host defense mechanisms. Commonly applied in clinical labs and biomedical research for biomarker validation and disease mechanism studies.