title: Oral tolerance to contact allergens: a common occurrence? A review.
abstract: Experimental and clinical oral tolerance to contact allergens has been reported sporadically, most notably in respect of nickel, and is generally assumed to be an uncommon phenomenon. There has recently been increased understanding of the immunological mechanisms inducing and maintaining oral tolerance. There are several contact allergens, including fragrance, antioxidant, and preservative chemicals, to which subjects are exposed through both cutaneous and oral routes. We examine the possibility that oral tolerance to contact allergens may be more common than previously thought. Animal models of oral tolerance to contact allergens indicate that cutaneous exposure to small, subsensitizing doses of contact allergens might negate any subsequent attempts to induce tolerance by oral administration. Extrapolating these observations to common human practises raises the possibility that application of contact allergens (fragrances, preservatives and antioxidants) in consumer products used by children could prevent or inhibit the later acquisition of specific tolerance resulting from 'natural' dietary exposure after weaning. Existing data on formaldehyde may conflict with this theory, though this could be explained by allergen specificity. We propose that further work in this area is needed.
authors: Department of Cutaneous Allergy, St. John's Institute of Dermatology, St. Thomas' Hospital, London SE1 7EH, UK. Jonathan.3.White@kcl.ac.uk
authors: Jonathan M L
authors: JM
authors: White
authors: Anthony T J
authors: AT
authors: Goon
authors: Ian R
authors: IR
authors: Jowsey
authors: David A
authors: DA
authors: Basketter
authors: Rose K H
authors: RK
authors: Mak
authors: Ian
authors: I
authors: Kimber
authors: John P
authors: JP
authors: McFadden
mesh_terms: D000284:Administration, Oral; D000485:Allergens / Q000008:administration & dosage / Q000276:immunology*; D000818:Animals; D017449:Dermatitis, Allergic Contact / Q000209:etiology / Q000517:prevention & control*; D005520:Food Preservatives / Q000008:administration & dosage; D006801:Humans; D007108:Immune Tolerance; D023421:Models, Animal; D009061:Mouth Mucosa / Q000276:immunology; D009532:Nickel / Q000008:administration & dosage / Q000276:immunology; D010476:Perfume / Q000008:administration & dosage; D011310:Preservatives, Pharmaceutical / Q000008:administration & dosage
chemical_list: D000485:Allergens; D005520:Food Preservatives; D010476:Perfume; D011310:Preservatives, Pharmaceutical; D009532:Nickel