title: What makes a chemical an allergen?
abstract: OBJECTIVE
  To consider the factors that confer on chemicals the ability to cause allergic sensitization, with particular emphasis on the induction of skin sensitization.
  
  
  METHODS
  Original and review articles available in the scientific literature.
  
  
  METHODS
  The expert opinion of the authors was used to select studies for inclusion in this review.
  
  
  RESULTS
  A number of requirements must be met if a chemical is to induce skin sensitization. The most important requirements are access to the viable epidermis, the formation of 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 influence the form of allergic sensitization.
  
  
  CONCLUSIONS
  An increasingly sophisticated understanding of the factors required for the development of skin sensitization and other forms of chemical-induced allergy provides new opportunities for toxicological investigation and clinical management.
authors.affiliation: Syngenta Central Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire, England. ian.kimber@syngenta.com
authors.forename: Ian
authors.initials: I
authors.lastname: Kimber
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Dearman
mesh_terms: D000485:Allergens / Q000276:immunology*; D016207:Cytokines / Q000096:biosynthesis; D017449:Dermatitis, Allergic Contact / Q000209:etiology* / Q000276:immunology; D006801:Humans; D007801:Langerhans Cells / Q000276:immunology; D008213:Lymphocyte Activation; D012867:Skin / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000485:Allergens; D016207:Cytokines