title: Ara h 8, a Bet v 1-homologous allergen from peanut, is a major allergen in patients with combined birch pollen and peanut allergy.
abstract: BACKGROUND
  We recently described patients with soybean allergy mainly mediated by cross-reactivity to birch pollen allergens. A majority of those patients were reported to have peanut allergy.
  
  
  OBJECTIVE
  We sought to study the occurrence of peanut allergy in patients allergic to birch pollen and characterized the Bet v 1-homologous peanut allergen Ara h 8.
  
  
  METHODS
  Recombinant Ara h 8 was cloned with degenerated primers and expressed in Escherichia coli. Nine Swiss and 11 Dutch patients with peanut and birch pollen allergy and a positive double-blind, placebo-controlled food challenge result to peanut were investigated for IgE reactivity to birch pollen and purified peanut allergens and cross-reactivity between birch and peanut. Ara h 8 stability against digestion and roasting was assessed by means of RAST inhibition. The IgE cross-linking potency of Ara h 8 was tested on the basis of basophil histamine release.
  
  
  RESULTS
  During double-blind, placebo-controlled food challenge, all patients experienced symptoms in the oral cavity, progressing to more severe symptoms in 40% of patients. CAP-FEIA detected recombinant (r) Ara h 8-specific IgE in 85%. IgE binding to Ara h 8 was inhibited by Bet v 1 in peanut extract immunoblotting and in RAST inhibition. In EAST inhibition recombinant rAra h 8 inhibited IgE binding to peanut in 4 of 7 tested patient sera. Antipeanut response was dominated by Ara h 8 in 12 of 17 tested patients. Furthermore, our results demonstrate a low stability of Ara h 8 to roasting and no stability to gastric digestion. Basophil histamine release with rAra h 8 was more than 20% in 5 of 7 tested sera.
  
  
  CONCLUSIONS
  Peanut allergy might be mediated in a subgroup of our patients by means of cross-reaction of Bet v 1 with the homologous peanut allergen Ara h 8.
authors.affiliation: Department of Dermatology, University Hospital, Zurich.
authors.forename: Diana
authors.initials: D
authors.lastname: Mittag
authors.forename: Jaap
authors.initials: J
authors.lastname: Akkerdaas
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Ballmer-Weber
authors.forename: Lothar
authors.initials: L
authors.lastname: Vogel
authors.forename: Marjolein
authors.initials: M
authors.lastname: Wensing
authors.forename: Wolf-Meinhard
authors.initials: WM
authors.lastname: Becker
authors.forename: Stef J
authors.initials: SJ
authors.lastname: Koppelman
authors.forename: André C
authors.initials: AC
authors.lastname: Knulst
authors.forename: Arthur
authors.initials: A
authors.lastname: Helbling
authors.forename: Susan L
authors.initials: SL
authors.lastname: Hefle
authors.forename: Ronald
authors.initials: R
authors.lastname: Van Ree
authors.forename: Stefan
authors.initials: S
authors.lastname: Vieths
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology*; D000595:Amino Acid Sequence; D001491:Basophils / Q000378:metabolism; D029662:Betula / Q000276:immunology*; D003429:Cross Reactions; D004311:Double-Blind Method; D005260:Female; D006636:Histamine Release; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D008297:Male; D008969:Molecular Sequence Data; D021183:Peanut Hypersensitivity / Q000209:etiology*; D010434:Pepsin A / Q000494:pharmacology; D011058:Pollen / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D000485:Allergens; D011994:Recombinant Proteins; D007073:Immunoglobulin E; D010434:Pepsin A