IL17A and Autoimmunity: Instead, CNS autoimmunity was long thought to be mediated by Th1 and Th17 cells through the production of IFNγ and IL-17 until the non-redundant function of T cell-derived GM-CSF in EAE was demonstrated in a number of publications (28, 41, 42); this led to the further discovery that T cells in MS show elevated GM-CSF production (43, 44).