AHR and cancer: Moreover, exogenous xenobiotic (e.g., BaP) or nutritional (e.g., indole-3-carbinole, I3C) but also endogenous AhR ligands (e.g., kynurenine, a product of tryptophan metabolism) can modulate innate and adaptive immunity, potentially resulting in either increased or decreased susceptibility to infection or cancer and may trigger autoimmune disorders and allergies (12).