064 New Zealand Black KN mouse, a novel model for autoimmune alopecia

A. Hiroi1, T. Ito2, T. Yoshimasu1, T. Otani1, N Seo2, K Uede1, F. Furukawa1 Dept. of Dermatology, Wakayama Medical University, Wakayama, Japan1 and Dept. of Dermatology, Hamamatsu University School of Medicine, Hamamatsu, Japan2

New Zealand Black (NZB)/KN mouse is an SLE-prone mouse associated with arthritis, and the male mouse shows alopecia spontaneously. We have reported that the male NZB/KN mouse is an autoimmune alopecia model, which suggests that the gender is an important factor influencing the development of alopecia. To verify the male predominance, we studied the relationship among alopecia, gender, and other clinical symptoms using NZB/KN, the F1 hybrid mouse with NZ White(NZW) mouse and the F2 hybrid mouse of (W/BKN F1×W/BKN F1). The incidence of alopecia of male NZB/KN, W/BKN F1, BKN/W F1, and F2 mice at 12 months (mo) were 88%, 9.5%, 0%, and 44% respectively. Male NZB/KN mouse initially developed hair loss and a slight indurative change around the tail, and then on the upper back. Fully developed alopecia lesion were observed in 25%, 75% at 3 mo and 6 mo. Hair density at alopecia lesion of male NZB/KN mouse was lower than it’s peripheral skin and control skin, although there was no difference in diameter. Histologically, intrafollicular lymphocyte infiltration were seen at the primary lesion and intradermal perivascular mononuclear cell infiltration were observed in the fully developed lesion. In the serum antibodies against follicular structure, mainly Ig M type, were detected at 3 mo, and 75% of male NZB/KN showed the positive titer until 12 mo. Immunofluorescence study revealed IgM deposition at basement membrane zone of both epidermis and/or hair follicle . In female NZB/KN mice a slight hair loss was found in 24% on the upper back at 12 mo, but the lesion was not fully developed. Female W/BKN F1, BKN/W F1, and F2 mice showed alopecia in 6%, 0%, and 7.3% respectively. F2 mice showed significant correlation among gender, alopecia and proteinuria, but not among alopecia, H-2, and splenomegaly. The alopecia in male NZB/KN mouse is a novel model of autoimmune alopecia and found to be closely associated with male gender based on the studies on F1 and F2 hybrid mice.