title: Clinical allergy to hazelnut and peanut: identification of T cell cross-reactive allergens.
abstract: BACKGROUND
  Peanut and tree nut allergies are life-threatening conditions for many affected individuals worldwide. Currently there is no cure. While co-allergy to peanut and tree nuts is a common clinical observation, and IgE cross-reactivity between peanut and tree nuts is reported, T cell cross-reactivity is poorly defined.
  
  
  METHODS
  Hazelnut-specific T cell lines were established using peripheral blood mononuclear cells from 5 subjects with co-allergy to hazelnut and peanut. These lines were stimulated with hazelnut and peanut extracts and purified major peanut allergens, Ara h 1 and Ara h 2. Proliferation was determined by (3)H-thymidine incorporation and secretion of key Th1 (IFN-γ) and Th2 (IL-5) cytokines analysed by ELISA.
  
  
  RESULTS
  Hazelnut-specific T cell lines from all 5 subjects proliferated upon stimulation with both hazelnut and peanut extracts and for 4 subjects, to Ara h 1 and/or Ara h 2. Proliferating cells were mainly CD4+ T cells and produced both IL-5 and IFN-γ in response to hazelnut and peanut stimulation. Mitogenicity of extracts and allergens was excluded by their lack of stimulation of house dust mite-specific T cells.
  
  
  CONCLUSIONS
  Our finding that hazelnut and peanut co-allergy is associated with cross-reactive T cell responses, driven partly by cross-reactivity to the major peanut allergens Ara h 1 and Ara h 2, points to future development of allergen immunotherapy by targeting cross-reactive T cells.
authors.affiliation: Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Vic., Australia.
authors.forename: Ian N
authors.initials: IN
authors.lastname: Glaspole
authors.forename: Maria P
authors.initials: MP
authors.lastname: de Leon
authors.forename: Sara R
authors.initials: SR
authors.lastname: Prickett
authors.forename: Robyn E
authors.initials: RE
authors.lastname: O'Hehir
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Rolland
mesh_terms: D055516:2S Albumins, Plant / Q000276:immunology; D000328:Adult; D000485:Allergens / Q000276:immunology*; D052179:Antigens, Plant / Q000276:immunology; D010367:Arachis / Q000276:immunology*; D002460:Cell Line; D031211:Corylus / Q000276:immunology*; D003429:Cross Reactions / Q000276:immunology; D005260:Female; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D015848:Interleukin-5 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D021184:Nut Hypersensitivity / Q000209:etiology / Q000276:immunology*; D021183:Peanut Hypersensitivity / Q000209:etiology / Q000276:immunology; D010940:Plant Proteins / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D055815:Young Adult
chemical_list: D055516:2S Albumins, Plant; D000485:Allergens; D052179:Antigens, Plant; C500889:Ara h 1 protein, Arachis hypogaea; C500890:Ara h 2 allergen, Arachis hypogaea; D006023:Glycoproteins; C508599:IL5 protein, human; D015848:Interleukin-5; D008565:Membrane Proteins; D010940:Plant Proteins; D007371:Interferon-gamma