Factors Influencing the Induction Phase of Skin Sensitization

The primary purpose of this review is to consider the factors that confer on chemicals the ability to induce skin sensitization and allergic contact dermatitis. It is clear that a number of requirements must be met if a chemical is to cause skin sensitization. Among the most important of these are access to the viable epidermis, protein reactivity (or conversion in the skin to a protein-reactive metabolite) and hence the ability to form stable conjugates with proteins, elicitation of cytokine production by skin cells, and the initiation of T-lymphocyte responses. In addition, qualitative aspects of induced immune responses will influence the form that allergic sensitization will take, and the conditions of exposure to the allergen may also result in the acquisition of specific immunologic tolerance rather than active sensitization. It is anticipated that an increasingly sophisticated understanding of the requirements for the development of skin sensitization and other forms of chemical-induced allergy will provide exciting new opportunities for toxicologic investigation and clinical management.