Interleukin 2 Receptor Alpha Chain (IL2RA)

The interleukin-2 receptor alpha chain (IL2RA), also known as CD25, is a type I transmembrane protein that binds interleukin-2 (IL-2). It is essential for the high-affinity binding of IL-2, a cytokine critical for T cell proliferation, survival, differentiation, and immune regulation. While the alpha chain binds IL-2 with low affinity on its own, it forms a high-affinity heterotrimeric complex with the beta and gamma chains, enabling potent cellular responses. CD25 is expressed on activated T cells, regulatory T cells (Tregs), activated B cells, and natural killer (NK) cells, with expression upregulated upon immune activation. A soluble form of CD25 exists and serves as a biomarker for immune activation. Targeting CD25 is being explored for therapeutic purposes, such as expanding regulatory T cells in autoimmunity.

Other names

CD25Tac antigenIL-2Rα

Agonist to stimulate downstream signaling through the IL-2 receptor complex; antagonists or antibodies to block IL-2 binding and subsequent signaling.