Interleukin-2 receptor alpha chain (IL2Ra, CD25) is a 55 kD glycoprotein expressed on activated T and B cells, thymocyte subsets, pre-B cells, and T regulatory cells. IL-2Ra combines with IL-2Rβ (CD122) and the common gamma chain (IL2Ry, CD132) to form the high affinity IL-2 receptor. Its affinity for IL2 and cellular functions are tightly regulated and vary in different cell types. Many hematological malignancies and possibly leukemic stem cells express IL-2Ra, which may enable oncogenic signaling. Immunotherapies targeting IL-2Ra expressed on Tregs and activated conventional T cells, have been investigated to treat cancers and autoimmune diseases. Clinical trials of the safety and efficacy of several novel IL-2Ra-directed antibody conjugates in hematological tumor indications are currently underway1. Thus, there is a need for pre-clinical models to evaluate the safety and efficacy of IL-2Ra-targeted therapeutics before they enter human trials.