Description
IL-2 receptor alpha chain (IL-2 Rα), also known as IL2RA, CD25 and TAC antigen, is a type I transmembrane glycoprotein. It is a component of high-affinity IL-2 receptors and thus is a key regulator of lymphocyte proliferation (1). IL-2 Rα is expressed on activated T cells and regulatory T cells and is capable of binding IL-2 with low affinity by itself. However, a ligand-induced high affinity heterotrimeric receptor complex is produced when IL-2 Rα is associated non-covalently with the IL-2 Rβ and IL-2 Rγ chains. Subsequently, the complex initiates intracellular signal pathways such as MAPK or JAK/STAT. IL-2 Rα is essential for regulation of both the size and content of the peripheral lymphoid compartment, probably by influencing the balance between clonal expansion and cell death following lymphocyte activation (2). Proteolytic processing of IL-2 Rα releases the entire extracellular domain thereby generating soluble IL-2 Rα (sIL-2 Rα). The secreted sIL-2 Rα is expressed on leukemia cells, lymphoma cells, newly activated T and B cells, as well as on approximately 10% of NK cells (3). Infection by the protozoan trypanosoma cruzi causes Chagas disease, characterized by a reduction in the amount of IL-2 Rα expressed on the surface of immune cells