ITGAX and infection: Using a novel knock-in mouse model for MyD88, we report here that MyD88 signaling in CD11c+ dendritic cells (DC) is sufficient to activate RORγt+ group 3 innate lymphoid cells (ILC3) as well as Th17/Th1 cells in response to infection with C. rodentium. In contrast, restricting functional MyD88 signaling to several other immune cell types, including macrophages (MO), T cells and ILC3 did not result in intestinal immunity, while expression of MyD88 in intestinal epithelial cells (IEC) mainly enhanced epithelial barrier integrity.