Used in immunology research to quantify soluble or cellular expression levels of CD25 (interleukin-2 receptor alpha) in human biological samples such as serum, plasma, or cell culture supernatants. This ELISA kit is particularly valuable in studies related to T cell activation, regulatory T cell function, and immune response modulation. It supports clinical and experimental investigations into autoimmune diseases, transplant rejection, and cancer immunotherapy by providing a reliable measure of immune system activation. The assay helps monitor biomarker levels in patient samples during therapeutic interventions targeting the IL-2 pathway.