Of all the known processes involving Th17 cells transdifferentiating into various effector cell types, including follicular helper T cells and regulatory T (Treg) cells, under inflammatory conditions8,9, conversion of Th17 cells into IL-17+IFN-γ+ cells (Th1-like Th17 cells) or IL-17-IFN-γ+ cells (Th1-like exTh17 cells) has been recognized as one of the major and critical pathways of Th17 cell plasticity during the development of autoimmune diseases in mice and humans2,6. This evidence concerns the gene IL17A and autoimmune disease.