Treg instability has been observed upon in vitro expansion resulting in the loss of FoxP3 expression and acquisition of effector functions (62–65, 77) and also notable numbers of IFN-γ-producing CD25+CD127− cells have been shown in patients suffering from MS (78), T1D (79), arthritis (80–82), psoriasis (83), or inflammatory bowel disease (84–86). Here, FOXP3 is linked to type 1 diabetes mellitus.