A type of
hair loss closely resembling human
alopecia areata has been described in C3H/HeJ mice. In order to test the assumed analogy with human
alopecia areata, we investigated the efficacy of treatment with the contact
allergen squaric acid dibutylester. In 12 C3H/HeJ mice with
alopecia areata an
allergic contact dermatitis was induced and elicited weekly on one side of the back by topical applications of
squaric acid dibutylester. Overt hair regrowth was observed only on the treated side of the back in nine of 12 mice. Histopathologic examination revealed a change in the distribution of the inflammatory infiltrate from a dense perifollicular lymphocytic infiltrate around the mid and lower regions of hair follicles in untreated skin to a uniform presence in the upper dermis in treated skin. Immunohistomorphometric studies revealed that treatment with
squaric acid dibutylester increased the CD4+/CD8+ ratio from approximately 1:2 in untreated
alopecia areata to 1:1 in treated
alopecia areata. Additional immunohistochemical investigations showed an aberrant expression of major histocompatibility complex class I, major histocompatibility complex class II and
intercellular adhesion molecule 1 on keratinocytes of the mid and lower parts of hair follicles in untreated
alopecia areata. In successfully treated skin ectopic major histocompatibility complex class I and II expression was clearly reduced, whereas
intercellular adhesion molecule 1 expression showed only minor changes. In conclusion,
alopecia areata-like
hair loss in C3H/HeJ mice responded to treatment with the contact sensitizer
squaric acid dibutylester analogous to human
alopecia areata. Moreover, successful treatment changes the aberrant expression of major histocompatibility complex class I and II in a way similar to that observed in human
alopecia areata. These observations support the concept that
alopecia areata-like
hair loss in C3H/HeJ mice can be utilized as an appropriate model for the study of human
alopecia areata.