Interleukin-2 receptor subunit alpha (Mouse) (IL-2Ra)

The mouse interleukin-2 receptor subunit alpha (IL-2Rα), also known as CD25, is a 55 kDa transmembrane glycoprotein that functions as the low-affinity monomeric receptor for interleukin-2 (IL-2) [UniProt: P01590, NCBI Gene: 16184]. While it binds IL-2 with a relatively low affinity (Kd ~10^-8 M) and lacks intrinsic signaling capabilities, it is essential for the assembly of the high-affinity heterotrimeric IL-2 receptor complex [PubMed: 2461345]. This complex, which includes the IL-2Rβ and IL-2Rγ chains, allows cells to respond to physiological concentrations of IL-2, driving T-cell expansion and differentiation [PubMed: 2461345]. In mice, IL-2Rα is constitutively expressed on regulatory T cells (Tregs) and is rapidly induced on effector T and B cells following antigen stimulation [PubMed: 15634887]. Consequently, it serves as a critical therapeutic target for modulating immune responses, particularly in preventing organ transplant rejection and treating autoimmune conditions [PubMed: 15634887, FDA: Basiliximab]. Drugs targeting this receptor work by either blocking the IL-2 binding site to prevent T-cell proliferation or by depleting CD25-positive cells through immune-mediated mechanisms [PubMed: 11160677, FDA: Daclizumab]. In research, anti-mouse CD25 antibodies like PC61 are standard tools for investigating the role of Tregs in cancer and infectious diseases [PubMed: 11160677]. Monitoring soluble CD25 levels or surface expression remains a vital biomarker for assessing immune activation and treatment efficacy [PubMed: 22460739].

Other names

CD25Ly-43p55Tac antigenIL2RA

Competitive inhibition of IL-2 binding to the high-affinity receptor complex and depletion of CD25-expressing cells via antibody-dependent cellular cytotoxicity (ADCC).