Intestinal epithelial lymphocytes (IELs) are responsible for maintaining gut barrier function as well as regulating the microbial burden in the lumen. In Cell Veldhoen and colleagues reveal that diet-derived compounds can in turn regulate IEL populations, with important consequences for immunohomeostasis. They observe that IELs have high basal amounts of the xenobiotic sensor aryl hydrocarbon receptor (AhR). The absence of AhR does not have any generalized effects on IELs but rather results in their specific loss from mucosal surfaces. The authors identify the phytochemical I3C as an important dietary source of AhR ligands. Dietary exclusion of I3C reduces mucosal populations of IELs and leads to perturbed microbial colonization and exacerbated gut inflammation. I3C and related compounds are particularly abundant in cruciferous vegetables such as cabbages, and these findings therefore reveal a direct mechanistic link between diet, intestinal immunity and the microbiota.

Cell (11 October 2011) doi:10.1016/j.cell.2011.09.025