Intermediate-affinity interleukin-2 receptor complex (IL-2Rβγ) (IL-2Rβγ)

The intermediate-affinity interleukin-2 receptor complex is a dimeric protein assembly composed of the interleukin-2 receptor subunit beta (CD122) and the cytokine receptor common subunit gamma (CD132) (UniProt: P14784, P31785). Unlike the high-affinity trimeric complex that includes the alpha subunit (CD25), the intermediate-affinity version is predominantly expressed on resting effector CD8+ T cells and natural killer (NK) cells (PubMed: 12446022). Its primary biological role is to mediate signal transduction via the JAK/STAT pathway, specifically activating JAK1 and JAK3 to phosphorylate STAT5, which leads to the proliferation and activation of these cytotoxic immune cells (PubMed: 30635454). In oncology, this complex is a critical therapeutic target for "biased" interleukin-2 formulations designed to selectively stimulate anti-tumor immunity while avoiding the activation of immunosuppressive regulatory T cells (Tregs) that preferentially express the high-affinity receptor (PubMed: 22391954). By bypassing the alpha subunit, these therapies aim to enhance efficacy and reduce the severe toxicities, such as vascular leak syndrome, historically associated with high-dose interleukin-2 treatment (PubMed: 30635454). This receptor complex thus serves as a pivotal switch in balancing immune activation versus suppression in the treatment of cancer and chronic infections.

Other names

IL-2R beta-gamma complexCD122/CD132 complexInterleukin-2 receptor subunit beta/common gamma chain complex

Agonism of the dimeric beta-gamma receptor complex to trigger the JAK/STAT signaling pathway, specifically promoting the expansion of effector T cells and natural killer cells while minimizing the activation of regulatory T cells (PubMed: 30635454).