Th17 helper T cells: a new actor on the stage of type 2 diabetes and ageing?

In late 1980s, Mosmann and Coffman1 proposed the T helper 1 cell (Th1) and Th2 cell theory. Th1 cells produce interferon-γ (IFN-γ) and induce CD8+ cytotoxic T cells and macrophages to fight against intracellular pathogens (cell-mediated immunity), while Th2 cells produce interleukin-4 (IL-4), IL-5, -10, and -13 and stimulate B cell to become plasma cells to secrete antibodies against extracellular pathogen such as parasites (humoral immunity).