Skin as a novel route for allergen-specific immunotherapy.

Subcutaneous allergen specific immunotherapy is an effective treatment of IgE-mediated allergies, but it requires repeated allergen injections with a risk of systemic allergic reactions. Other routes of immunization had been explored to improve patient compliance and safety. Skin is not only a physical barrier between the body and outside world, but also an important immune organ eliciting innate and adaptive immune function. Skin has been used as an ideal site for vaccination of infectious diseases. Food allergen topically applied onto disrupted skin can induce sensitization and food allergy would develop subsequently. However, immune tolerance would be induced if the skin barrier is kept intact. Several mice and human studies on epicutaneous immunotherapy showed successful treatment on IgE-induced allergy models or allergic diseases. Migratory Langerhans cells might play a decisive role in the induction of different immune responses. Further research on the underlying mechanism of the crosstalk between skin and gut or airway is helpful for the understanding of many protective or sensitizing immune responses induced via skin, and also is helpful for the development of new strategy for the treatment of allergic disease.