title: Identification of hazelnut major allergens in sensitive patients with positive double-blind, placebo-controlled food challenge results.
abstract: BACKGROUND
  The hazelnut major allergens identified to date are an 18-kd protein homologous to Bet v 1 and a 14-kd allergen homologous to Bet v 2. No studies have reported hazelnut allergens recognized in patients with positive double-blind, placebo-controlled food challenge (DBPCFC) results or in patients allergic to hazelnut but not to birch.
  
  
  OBJECTIVE
  We characterized the hazelnut allergens by studying the IgE reactivity of 65 patients with positive DBPCFC results and 7 patients with severe anaphylaxis to hazelnut.
  
  
  METHODS
  Hazelnut allergens were identified by means of SDS-PAGE and IgE immunoblotting. Further characterization was done with amino acid sequencing, evaluation of the IgE-binding properties of raw and roasted hazelnut with enzyme allergosorbent test inhibition, assessment of cross-reactivity with different allergens by means of immunoblotting inhibition, and purification by means of HPLC.
  
  
  RESULTS
  All the sera from the patients with positive DBPCFC results recognized an 18- and a 47-kd allergen; other major allergens were at molecular weights of 32 and 35 kd. Binding to the 18-kd band was inhibited by birch extract, indicating its homology with the birch major allergen, and abolished in roasted hazelnut. The 47-kd allergen is a sucrose-binding protein, the 35-kd allergen is a legumin, and the 32-kd allergen is a 2S albumin. Patients with severe anaphylactic reactions to hazelnut showed specific IgE reactivity to a 9-kd allergen, totally inhibited by purified peach lipid-transfer protein (LTP), which was heat stable and, when purified, corresponded to an LTP.
  
  
  CONCLUSIONS
  The major allergen of hazelnut is an 18-kd protein homologous to Bet v 1, and the 9-kd allergen is presumably an LTP. Other major allergens have molecular weights of 47, 32, and 35 kd.
authors.affiliation: Allergy Center, 3rd Division of General Medicine, Ospedale Maggiore IRCCS, Milan, Italy.
authors.forename: Elide A
authors.initials: EA
authors.lastname: Pastorello
authors.forename: Stefan
authors.initials: S
authors.lastname: Vieths
authors.forename: Valerio
authors.initials: V
authors.lastname: Pravettoni
authors.forename: Laura
authors.initials: L
authors.lastname: Farioli
authors.forename: Chiara
authors.initials: C
authors.lastname: Trambaioli
authors.forename: Donatella
authors.initials: D
authors.lastname: Fortunato
authors.forename: Dirk
authors.initials: D
authors.lastname: Lüttkopf
authors.forename: Marianna
authors.initials: M
authors.lastname: Calamari
authors.forename: Raffaella
authors.initials: R
authors.lastname: Ansaloni
authors.forename: Joseph
authors.initials: J
authors.lastname: Scibilia
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Ballmer-Weber
authors.forename: Lars K
authors.initials: LK
authors.lastname: Poulsen
authors.forename: Brunello
authors.initials: B
authors.lastname: Wütrich
authors.forename: Kirsten Skamstrup
authors.initials: KS
authors.lastname: Hansen
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Robino
authors.forename: Claudio
authors.initials: C
authors.lastname: Ortolani
authors.forename: Amedeo
authors.initials: A
authors.lastname: Conti
mesh_terms: D000485:Allergens / Q000009:adverse effects* / Q000737:chemistry* / Q000276:immunology; D000595:Amino Acid Sequence; D000707:Anaphylaxis / Q000175:diagnosis / Q000209:etiology; D003429:Cross Reactions; D004311:Double-Blind Method; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000097:blood; D008969:Molecular Sequence Data; D021184:Nut Hypersensitivity / Q000175:diagnosis / Q000209:etiology*; D009754:Nuts / Q000009:adverse effects* / Q000737:chemistry* / Q000276:immunology
chemical_list: D000485:Allergens; D007073:Immunoglobulin E