Regulatory T cells function in multiple biological contexts, including autoimmunity, cancer, acute and chronic infections, host–commensal interactions and inflammation at barrier sites, allergy, pregnancy, tissue repair, metabolic sterile inflammation, and ... Regulatory T cells function in multiple biological contexts, including autoimmunity, cancer, acute and chronic infections, host–commensal interactions and inflammation at barrier sites, allergy, pregnancy, tissue repair, metabolic sterile inflammation, and allo-transplantation. George Plitas, and Alexander Y. Rudensky Cancer Immunol Res 2016;4:721-725 ©2016 by American Association for Cancer Research