IL21 and infection: Studies in a TH2-biased murine model of infection with H. polygyrus further confirmed that the two main cytokines secreted by TFH cells, IL-21 and IL-4, can cross-regulate the expression of T-bet and CD11c in the absence of an intact IFN-γ/IFN-γR signaling axis (Naradikian et al., 2016).