Conversely, under hypoxia from protracted inflammation, the AhR ligation by UCB in pathogenic Th17 cells from Crohn’s disease patients results in HIF-1α-dependent CD39 downregulation and defective immunosuppression in response to UCB due to resistance of Th17 cells to AhR signaling and induction of ATP-binding cassette (ABC) transporters () (35). The gene discussed is AHR; the disease is Crohn disease.