Successful treatment of alopecia areata-like hair loss with the contact sensitizer squaric acid dibutylester (SADBE) in C3H/HeJ mice

A type of hair loss closely resembling human alopecia areata has been descr ibed in C3H/HeJ mice. In order to test the assumed analogy with human alope cia areata, we investigated the efficacy of treatment with the contact alle rgen 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 r egrowth was observed only on the treated side of the back in nine of 12 mic e. 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. Immunohistomorphometr ic studies revealed that treatment with squaric acid dibutylester increased the CD4(+)/CD8(+) ratio from approximately 1:2 in untreated alopecia areat a to 1:1 in treated alopecia areata. Additional immunohistochemical investi gations showed an aberrant expression of major histocompatibility complex c lass I, major histocompatibility complex class II and intercellular adhesio n molecule 1 on keratinocytes of the mid and lower parts of hair follicles in untreated alopecia areata. In successfully treated skin ectopic major hi stocompatibility complex class I and II expression was clearly reduced, whe reas intercellular adhesion molecule 1 expression showed only minor changes . In conclusion, alopecia areata-like hair loss in C3H/HeJ mice responded t o treatment with the contact sensitizer squaric acid dibutylester analogous to human alopecia areata. Moreover, successful treatment changes the aberr ant expression of major histocompatibility complex class I and II in a way similar to that observed in human alopecia areata. These observations suppo rt the concept that alopecia areata-like hair loss in C3H/HeJ mice can be u tilized as an appropriate model for the study of human alopecia areata.