Picryl chloride-induced allergic dermatitis in IQI/Jic female mice

IQI/Jic (IQI) mice are an ICR-derived inbred strain developed in Japan, and it is known that aged females of this strain develop allergic dermatitis o f spontaneous nature. In the present study, young IQI female mice which wer e sensitized with picryl chloride (PCL) to the shaved skin of abdomen and t hen topically applied with PCL to the ear at 4, 11, 18 and 25 days after th e sensitization were examined. The ear swelling response increased rapidly after the Ist application, peaked after the 2nd one, and then gradually dec reased. Histopathologically, edema with inflammatory cell infiltration deve loped after the Ist application and progressed after the 2nd one. The numbe r of mast cells, CD4-positive cells and MHC class II-positive cells became prominent accompanied with epidermal thickening and dermal fibroplasia afte r the 4th application when clear elevation of total serum IgE levels was ob served in many mice. Compared with the dermatitis induced in the same way i n BALB/c female mice, the nature was similar with each other but the degree was obviously severer in IQI female mice. IQI female mice are considered t o be a useful laboratory animal for the investigation of allergic dermatiti s.