IL21 and tuberculosis: Th2 and Th17-like T follicular helper(TFH) subsets were shown to produce large levels of IL-21, a cytokineinvolved in CD8 T-cell priming in tuberculosis that induces switching predominantlyto IgG1 and IgG3 isotypes (Tangye et al.2013, Booty et al. 2016).