More recently, a novel immunotherapy based on subcutaneous administration of low-dose recombinant human IL-2 (r-IL2, (Aldesleukin/Proleukin) has shown potent immunosuppressive effects in patients with autoimmune pathologies (139), including Type I diabetes (140), hepatitis C-associated vasculitis (141), SLE (142–145), and chronic graft-versus-host disease (146–148). Here, IL2 is linked to chronic graft versus host disease.