A mouse model of the atopic eczema/dermatitis syndrome by repeated application of a crude extract of house‐dust mite <i>Dermatophagoides farinae</i>

Background: We cultured Dermatophagoides farinae (Df), one of the most common mites in house dust and the most important allergen among natural allergens. With this material, we attempted to produce an animal model of the atopic eczema/dermatitis syndrome (AEDS). Methods: We cultured Df mites in high density and prepared a crude extract of Df (DfE) together with the culture medium. We applied the extract to the back skin of NC/Nga and BALB/c mice three times per week for 8 weeks. Results: In the NC/Nga group, dryness or scaling appeared on the skin, and scratching behavior increased at the second week in the DfE‐treated group. Skin erosion and hemorrhage occurred at the fourth week. The epidermis thickened and deepened into the upper dermis, in which mast cells were highly accumulated, corresponding with the skin lesion of AEDS patients. Specific IgE and IgG to DfE and total IgE were elevated in the sera. Mice treated with an extract of mite culture medium did not develop skin lesions. In the BALB/c group, mice developed specific IgE and IgG to DfE, however, no typical skin lesions appeared. Mast cells in the upper dermis did not increase. Conclusions: Repeated painting of Dermatophagoides extract produced IgE‐associated AEDS‐like lesions on the skin of NC mice.