The interleukin 2 receptor alpha (IL2RA), also called CD25, is a type I transmembrane protein that presents on activated T cells, activated B cells, some thymocytes, myeloid precursors, and oligodendrocytes. IL2RA is a member of cytokine receptors family that utilizes the common gamma chain subunit (γc). IL2RA is expressed in most B-cell neoplasms, some acute nonlymphocytic leukemias, neuroblastomas, and tumor infiltrating lymphocytes. IL2RA associates with IL2RB (CD122) to form a heterodimer that can act as a high-affinity receptor for IL-2.