Used in immunological research to quantify levels of soluble interleukin-2 receptor alpha (sCD25) in biological samples such as serum, plasma, or cell culture supernatants. This ELISA kit helps monitor immune system activation, as elevated sCD25 levels are associated with T-cell activation and various autoimmune diseases, transplant rejection, and certain cancers. It is widely used in clinical research and drug development to assess immune response and treatment efficacy.