New concepts in cutaneous allergy.

Allergic contact dermatitis affects a worrying proportion of the general population. The mechanisms underlying this chemical-triggered delayed-type hypersensitivity are still not fully understood. In recent years, basic research has shown that the immune system reacts to contact allergens by activation of signalling pathways that are usually used to fight infections. Ongoing work is aimed at the elucidation of the path that leads from the chemistry of contact allergens to the inflammatory skin disease. The cellular players and their complex interactions are being characterized. Proteins are being identified whose chemical modification by contact allergens results in the activation of signalling pathways involved in pathogenesis. Pathway identification is supported by genomic and proteomic techniques. All of these efforts will yield a cellular and molecular understanding of the orchestration of the innate and adaptive immune response to contact allergens. This knowledge will help in the identification of gene and protein signatures for improved diagnostics, the identification of novel drug targets for targeted treatments, as well the development of in vitro assays for contact allergen identification.