New aspects of the molecular basis of contact allergy.

PURPOSE OF REVIEW: The aim of the review is to provide an up-to-date scenario of the mechanisms governing contact allergy, a widely diffused immune response to small chemicals (haptens) penetrating the skin. RECENT
FINDINGS: The availability of animal models for contact allergy, such as murine contact hypersensitivity, is of great importance in understanding the pathomechanisms of the allergic response, although all these findings need confirmation in humans. Contact allergy is the result of the activation of both innate and adaptive immunity in response to haptens. Both skin resident cells, such as keratinocytes and mast cells, and immigrating leucocytes, including T lymphocytes and natural killer cells, actively participate in the reaction. Different types of T-regulatory cells appear to be crucial in the prevention of contact allergy or in the early termination of the reaction. Understanding the mechanisms that regulate immune responses to haptens is critical for the development of innovative therapeutic approaches.
SUMMARY: Although contact allergy is predominantly a T-cell-mediated disease, humoral immune responses and innate immunity actively participate in the initiation and expression of the allergic disease.