BCL6 and infection: Consequently, Bcl6-knockout mice displayed a significant decrease in the differentiation (and survival) of Tfh cells, with increased the differentiation of Th1 cells, which are involved in cell-mediated responses to intracellular infections, Th2 cells, which mediate humoral immune responses to extracellular parasites, and Th17 cells, which respond to extracellular infections at mucosal surfaces as well as tissue injury [2,4,58].