IL2 Receptor beta (CD122) is a member of the immunoglobulin superfamily that forms the high affinity IL2 receptor with CD25 and CD132. This receptor chain, which is also shared by the IL15 receptor, is constitutively expressed by NK cells and at lower levels by T cells, B cells, monocytes, and macrophages. The IL2 Receptor beta chain can combine with either the common gamma subunit (gamma c) alone or the gamma c subunit and the IL2 Receptor alpha subunit to generate intermediate or high affinity IL2 receptor complexes, respectively. CD122 levels can be upregulated by activation stimuli such as IL2.