IL21 and Autoimmunity: Besides their cytolytic activity, fCD8 cells can promote isotype switching of B cells in the settings of autoimmunity (Valentine et al., 2018) while IL‐6, a positive regulator of Tfh cells (Eto et al., 2011), can also induce IL21‐producing CD8 T cells with follicular helper function (Yang et al., 2016) and therefore further induce humoral responses indirectly through local IL21 production.