DCs play central roles in the maintenance of tolerance and the generation of protective immune responses against pathogens in the gut as well as in other tissues.78,79 AHR is highly expressed in DCs,80 affecting their differentiation and function.9,81 AHR-driven cytokine, kynurenine,82–84 and retinoic acid85 production in DCs boosts the differentiation of regulatory T cells that suppress the development of experimental autoimmune encephalomyelitis (EAE), the model of multiple sclerosis (MS).86 This evidence concerns the gene AHR and myeloid sarcoma.