Regulation of cutaneous allergic reaction by odorant inhalation

Olfactory stimuli modulate emotional conditions and the whole body immune s ystem. Effects of odorant inhalation on cutaneous immune reaction were exam ined. Contact hypersensitivity to 2,4,6-trinitrochlorobenzene was elicited in C57BL/6 mice. The reaction was suppressed at both the induction and elic itation phases by exposure to an odorant, citralva. Topical application of citralva or lyral/lilial did not affect the reaction. The suppressive effec t of citralva was more potent than that of another odorant, lyral/lilial. C itralva decreased the number of epidermal Langerhans cells, whereas lyral/l ilial had a weak effect. Citralva but not lyral/lilial induced plasma corti costerone. Glucocorticoid receptor antagonist abrogated the suppressive eff ect of citralva on contact hypersensitivity. Serum interleukin-12 was downr egulated by exposure to citralva or lyral/lilial. These data demonstrate th at olfactory stimuli regulate the cutaneous immune system.