CD25/IL-2Ralpha Fc Chimera, Human

The IL-2 receptor system consists of three non-covalently linked subunits termed IL-2Ralpha, IL-2Rbeta, and IL-2Rgamma. The IL-2Ralpha is a type I transmembrane protein consisting of a 219 amino acid (a.a.) extracellular domain, a 19 a.a. transmembrane domain and a 13 a.a. intracellular domain, which is not involved in the transduction of IL-2 signal. Activated T cells, regulatory T cells (Tregs) and NK cells express high levels of CD25 and expression of the high-affinity IL-2Ralpha is mostly limited to these cell populations. Signaling via IL-2Ralpha mediates multiple biological processes in various cell populations, e.g. proliferation and differentiation of B cells and NK cells. A soluble form of IL-2Ralpha (IL-2Ralpha) appears in serum, concomitant with its increased expression on cells. The function of the soluble IL-2Ralpha is unclear. Increased levels of IL-2Ralpha in biological fluids reportedly correlate with increased T and B cell activation and immune system activation. Increased serum concentration of IL-2Ralpha has been observed in patients with a variety of inflammatory conditions and in the course of some leukemias and lymphomas.