To elucidate whether the aggravation of dermatitis and pruritus induced by FA exposure is related to the changes in the skin Th2 cytokines, such as IL-4, -5, and -13 as well as IL-17A and TSLP, we examined whether exposure to 1.2 ppm of FA increased the expression of IL-4, IL-5, IL-13, IL-17A and TSLP in AD and naive rats. The gene discussed is IL4; the disease is dermatitis.