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Aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor, connecting environmental stimulators with the immune system. M1 macrophages are a part of immune system that contribute to the inflammatory events in the pathogenesis of Behcet's disease (BD). The effect of AHR on the macrophages in BD patients is still unclear. In this study, we investigated the mRNA expression of AHR in the monocyte-derived and M1 macrophages in active BD patients in comparison to healthy controls. Isolated monocytes from 10 healthy controls and 10 active BD patients were differentiated to macrophages by macrophage-colony stimulating factor (M-CSF) for 7 days. Cells were then polarized to M1 macrophages by lipopolysaccharide (LPS) and interferon-γ (IFNγ) for 24h. Monocyte purity and macrophage markers expression were analyzed by flow cytometry. Analysis of AHR mRNA expression was performed by SYBR Green real-time PCR. Our results showed that AHR expression is significantly down-regulated in M1 macrophages compare to monocyte-derived macrophages. It was shown that both monocyte-derived macrophages and M1 macrophages from BD patients significantly express lower level of AHR mRNA compared to healthy individuals. Our results demonstrate an anti-inflammatory role for AHR in macrophages, which suggest that decreased AHR expression is associated with pro-inflammatory M1 macrophage and BD susceptibility.