Several clinical trials have demonstrated that low-dose IL-2 can selectively expand Tregs without significantly affecting effector T cells in patients with various autoimmune conditions.340 In a phase 1/2 trial involving patients with ulcerative colitis, low-dose IL-2 treatment resulted in significant clinical improvement in 50% of patients, accompanied by expansion of FOXP3+ Tregs.341 However, challenges remain regarding the optimal dosing regimen, potential off-target effects, and long-term efficacy of this approach. This evidence concerns the gene IL2 and ulcerative colitis.