Interleukin-2 receptor subunit alpha (IL-2Rα) (IL-2Rα)

Interleukin-2 receptor subunit alpha (IL-2Rα), also known as CD25, is a type I transmembrane protein that functions as the high-affinity component of the heterotrimeric interleukin-2 (IL-2) receptor complex [1, 12]. While IL-2Rα does not directly participate in signal transduction, its presence increases the binding affinity of the IL-2 receptor for its ligand by approximately 100-fold compared to the intermediate-affinity beta-gamma dimer [4, 8]. This high-affinity interaction is essential for the proliferation of activated T cells and the survival of regulatory T cells (Tregs), which maintain immune tolerance [2, 12]. Clinically, IL-2Rα is a major therapeutic target; monoclonal antibodies like basiliximab and daclizumab act as antagonists to prevent organ transplant rejection and treat autoimmune conditions by blocking IL-2-mediated T-cell activation [3, 5, 10]. In oncology, IL-2Rα is utilized as a target for immunotoxins in hematologic malignancies, although its expression on Tregs can also limit the efficacy of IL-2-based cancer immunotherapies [5, 7, 17]. Additionally, the soluble form of the receptor (sIL-2R) serves as a critical biomarker for monitoring immune activation and disease progression in various inflammatory and malignant disorders [15, 18].

Other names

CD25Tac antigenp55IL2RAIL2RIDDM10TCGFRIMD41

IL-2 receptor antagonism to prevent T-cell activation; IL-2 receptor agonism to stimulate immune responses; Targeted cytotoxicity via IL-2Rα-directed immunotoxins or antibody-drug conjugates.