title: HLA-DR expression is induced on keratinocytes in delayed hypersensitivity but not in allergen induced late-phase reactions.
abstract: In view of increasing evidence suggesting an active immunoregulatory role of the skin keratinocytes and the observation that the differentiation of allergen specific T lymphocytes is critical in the development of allergy, we evaluated epidermal expression of HLA-DR antigen in skin reactions induced with an atopen (house dust mite) and with an non-atopic antigen (Hemocyanin). Two groups of patients with house dust mite (Dermatophagoides pteronyssinus [Der p]) allergy were compared, one group was skin tested with Der p, the other group was immunized and subsequently skin tested with Helix pomatia Hemocyanin (HPH). Biopsy specimens taken at 48 h after the HPH (n = 11) and Der p (n = 11) tests were analysed immunohistologically. Reactions in both groups were comparable in size. Immunohistological analysis showed domination by CD4+ lymphocytes. Expression of HLA-DR antigen by epidermal keratinocytes was observed in six out of 11 of the HPH induced reactions, but in none of the Der p induced reactions. Eosinophils were spotted only throughout the Der p induced reactions, showing a good correlation with the number of CD4 positive lymphocytes. The lack of HLA-DR expression by keratinocytes during the allergen-induced reaction, compared with the Hemocyanin induced reaction can be the result of a difference in cytokine profile of the lymphocytes dominating the dermal infiltrate. On the other hand evidence exists that defective HLA-DR expression by keratinocytes enhances antigen induced lymphocyte activation, and may thus contribute to the development of allergen-specific T-lymphocytes.
authors.affiliation: Department of Pulmonology, University of Amsterdam, the Netherlands.
authors.forename: F R
authors.initials: FR
authors.lastname: Weller
authors.forename: M C
authors.initials: MC
authors.lastname: De Jong
authors.forename: M S
authors.initials: MS
authors.lastname: Weller
authors.forename: K
authors.initials: K
authors.lastname: Heeres
authors.forename: J G
authors.initials: JG
authors.lastname: De Monchy
authors.forename: H M
authors.initials: HM
authors.lastname: Jansen
mesh_terms: D000485:Allergens / Q000009:adverse effects; D000818:Animals; D039741:Antigens, Dermatophagoides; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D017449:Dermatitis, Allergic Contact / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D004804:Eosinophils / Q000276:immunology; D006023:Glycoproteins / Q000009:adverse effects*; D006684:HLA-DR Antigens / Q000096:biosynthesis*; D006372:Helix, Snails / Q000276:immunology; D006433:Hemocyanins / Q000009:adverse effects*; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D007124:Immunoenzyme Techniques; D016130:Immunophenotyping; D015603:Keratinocytes / Q000378:metabolism*; D008925:Mites / Q000276:immunology; D012867:Skin / Q000378:metabolism / Q000473:pathology; D012882:Skin Tests
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D006023:Glycoproteins; D006684:HLA-DR Antigens; D006433:Hemocyanins