The transcription factor aryl hydrocarbon receptor (AhR) is selectively expressed in some immune cells, importantly in both Th17 and gamma/delta T cells. Its activation is important for optimal development of the Th17 cell subset and results in enhanced activation of both Th17 and IL-17 producing gamma/delta T cells. Immune protection against invading microorganisms starts at epithelial barrier sites. At these sites reside specialised intra-epithelial lymphocytes (IELs) that are important not only as a first line of defence but also in epithelial barrier organisation and wound repair. Especially at epithelial sites, AhR activation in response to endogenous and exogenous ligands may constitute a way in which environmental stimuli could affect the immune status. New data regarding the role of such stimulation will be discussed.
Disclosure of Interest None Declared