Fuente: WIPO "tomato" Provided herein are materials and methods for determining responsiveness of any therapy that enhances regulatory T cell (Treg) function in the treatment of inflammatory bowel disease (IBD). The materials and methods provided herein may be used to determine low dose IL- 2 responsiveness in a subject having an inflammatory bowel disease. The materials and methods can be used to determine low dose IL- 2 responsiveness in a blood sample prior to administering a low dose IL-2 therapy.