IL-2 mutein with diminished CD25 binding expands regulatory T cells and blocks autoimmunity

Abstract Since its identification, IL-2 has been tested as a therapy for both oncology and autoimmunity as it has the ability to expand effector T cells and NK cells as well as regulatory T cells (Tregs). Due to its toxicity, IL-2 has been the focus of molecular engineering to improve its therapeutic properties and expand its therapeutic index. To target CD4+CD25− and CD8+CD25− T cells, we rationally designed a murine and a human IL-2 variant to bind the IL-2Rβγ (IL2Rbg) heterodimer without binding to IL-2Rα (IL2Ra CD25). The mutein demonstrated reduced binding to CD25 and reduced ability to induce phosphorylation of STAT5 in Tregs while maintaining binding to IL-2Rbgc. Despite these results, the IL-2-mutein exhibited significant expansion of CD25+Foxp3+ T cells. To demonstrate biological relevance of these regulatory T cells, with two different dosing regimens, the IL-2-mutein completely blocked incidence of hyperglycemia in NOD mouse. These data suggest the identified IL-2.mutein is a potent anti-inflammatory in vivo.