CD25 is expressed by activated T cells, B cells, and monocytes. Tregs, responsible for regulating immune tolerance, express the highest amounts of CD25. CD25 is the IL-2 receptor α chain, which functions as one subunit of the high-affinity variant of the IL-2 receptor. When cleaved off by proteases, the soluble receptor (sIL-2Rα) is released extracellularly. Soluble CD25 has a low affinity for IL-2 and can function either as a decoy receptor reducing the activity of IL-2 or by enabling trans presentation to cells expressing the dimeric, intermediate-affinity IL-2R. Increased levels of soluble CD25 indicate ongoing immune responses, and therefore CD25 has been investigated as a biomarker for disease. For example, elevated sCD25 levels have been associated with autoimmune disorders, severe COVID-19, and some types of cancer.
| Alternative analyte names: | CD25, cluster of differentiation 25, Interleukin-2 receptor subunit alpha, IL2RA, Tac |
| Cell types: | T cell |
| Products: | Click here to see our portfolio of CD25 (IL-2Rα) products. |