We and another group have previously reported that repeated application of house dust mite extract or FAg onto the skin of NC/Nga mice also causes AD-like dermatitis and leads to an increase in mRNA expression of IFN-γ as well as Th2 cytokines such as IL-4, IL-5, and IL-13, effectively and reproducibly [24, 28]; thus, we explored FAg-induced dermatitis in the NC/Nga mouse ear. This evidence concerns the gene IL4 and dermatitis.