CD25 is the α chain of the heterotrimeric IL-2 receptor and is highly expressed in many types of hematologic malignancies but shows low expression in most solid tumors. CD25 is also abundantly expressed on activated circulating immune cells and regulatory T cells (Tregs). The infiltration of Tregs into the tumor microenvironment can lead to an imbalance in the ratio of effector T cells (Teffs) to Tregs, which is associated with tumor progression. Restoring a balanced Teff/Treg ratio may enhance the efficacy of immunotherapy. As a potential target for Treg depletion, CD25 plays a critical role in the development of novel immunotherapeutic strategies.
