IL21 and infection: Therefore, the CXCR5+ Tfh-like phenotype found in IFN-γ+ cells is likely to be a consequence of Bcl6-inducing cytokines (such as IL-6, IL-21 or IL-27) or B:T cell interactions involving ICOS, which is also highly upregulated on all effector cells in this infection, and is reported to promote Tem survival [61].