The aryl hydrocarbon receptor (AhR) is an important transcription factor mediating detoxification of environmental toxins,including polyaromatic hydrocarbons, by inducing cytochromeP450 oxygenases. It is particularly active at environmental interfaces including the skin and mucosal tissue (1). More recently, theAhR has been implicated in further immune processes includingcontact sensitivity, autoimmunity, tumor immunity, allergy andinfection