Pathology of spontaneous dermatitis in CBy.ALY-aly mice.

CBy.ALY-aly/aly (C-aly) mice develop progressive dermatitis in areas of the face and dorsal neck from around three months of age. Staphylococcus aureus was detected in the skin lesions of C-aly mice. However, even when the mice were raised under S. aureus free conditions, a similar, though less severe, dermatitis was still observed. The mice showed a marked increase in the number of eosinophils in the peripheral blood and skin lesions, with no changes in plasma IgE levels. These findings suggest that the dermatitis of these mice may be an atypical allergic condition with little or no involvement of IgE. C-aly mice may be a useful animal model of chronic dermatitis or pruritus without elevated IgE levels.