The importance of the IL-21 expression by non-conventional TFH cells was reinforced by the observations that mice lacking γδ T-cells were incompetent to control P. berghei infection and that the lack of ability to control infection correlated with the findings that γδ T-cell-deficient mice had impaired levels of P. berghei-specific antibodies, decreased numbers of TFH cells and fewer GC B cell toward the later course of infection as compared with their C57BL/6 counterparts (Inoue et al., 2018). Here, IL21 is linked to infection.