The therapeutic role of contact sensitization in alopecia areata: What, how, and why?

The immunologic pathways by which a contact dermatitis is able to induce hair regrowth in alopecia areata are not completely understood. Novel studies, however, provided evidence that cytokines may play a pivotal role during the pathogenesis of alopecia areata, and a counteracting cytokine pattern induced by the contact dermatitis may be responsible for the inhibition of the immune response giving rise to alopecia areata. Such counteracting activities are most likely mediated by cytokines such as interleukin 10 or transforming growth factor β1. This hypothesis is as yet unproven, but the effectiveness of allergic contact dermatitis in the treatment of alopecia areata would be compatible with this concept.