Normalisation of hair follicle morphology in C3H/HeJ alopecia areata mice after treatment with squaric acid dibutylester

Alopecia areata is a non-scarring, reversible disorder, presumably caused b y an autoimmune attack on anagen hair follicles. Treatments are numerous, a nd most of these are ineffective. However, the elicitation of contact derma titis on the affected skin is commonly associated with hair regrowth. A maj or advance in the study of alopecia areata has been the introduction and ch aracterisation of the C3H/HeJ mouse model that exhibits many features of th e human disease. In this study we examined the effects of squaric acid dibutylester treatmen t on hair follicles and the associated leukocyte infiltrate in alopecia are ata mice by light and transmission electron microscopic analysis. This was compared with unaffected normal mice and alopecic untreated mice. Experimen tal mice were treated unilaterally with the contact allergen squaric acid d ibutylester and the skin was assessed after hair regrowth. The characterist ic pathological picture of alopecia areata was observed in alopecic but not normal mice. Nine of eleven experimental mice regrew hair on the treated s ide only and this was associated with a reduction in peri/intrafollicular i nflammatory cell infiltrates, hair follicle dystrophy, melanin incontinence /clumping, and an increase in the numbers of hair follicles in full anagen. This normalisation of hair follicle status after treatment reflects the suc cessful reversal of disease in these mice. The mechanism of action of topic al immunotherapy with a potent contact allergen such as squaric acid dibuty laster still needs to be elucidated, but an altered immune milieu is suspec ted. This study further validates the C3H/HeJ mouse model of alopecia areat a in the search for therapeutic interventions in this common hair follicle disorder.