title: IgE cross-reactivity between the major peanut allergen Ara h 2 and the nonhomologous allergens Ara h 1 and Ara h 3.
abstract: BACKGROUND
  Ara h 1, a vicilin; Ara h 2, a 2S albumin; and Ara h 3, a legumin, are major peanut allergens. Ara h 2 is an important predictor of clinical reactivity to peanut, but cosensitization to all 3 allergens is correlated with the severity of patients' symptoms.
  
  
  OBJECTIVE
  We investigated whether cosensitization to these 3 allergens is caused by IgE cross-reactivity, despite the fact that they do not display obvious structural or sequence similarities.
  
  
  METHODS
  IgE cross-inhibitions were performed with purified Ara h 1, Ara h 2, and Ara h 3 and IgG-depleted sera from 10 patients with peanut allergy. After an in silico search for similar peptides, IgE ELISA inhibition assays with synthetic peptides were performed.
  
  
  RESULTS
  Ara h 2 inhibited IgE binding to Ara h 1 (average, 86% ± 13%) and Ara h 3 (average, 96% ± 6%). IgE binding to Ara h 2 was inhibited by Ara h 1 by 78% ± 15% and by Ara h 3 by 80% ± 6%. A subsequent sequence comparison showed that these nonhomologous allergens contained several similar surface-exposed peptides. IgE binding to Ara h 2-derived peptides was completely inhibited by Ara h 1 and Ara h 3. A mixture of these peptides reduced IgE binding to Ara h 1 and Ara h 3 by 20% to 60% and to Ara h 2 by 49% to 89%.
  
  
  CONCLUSIONS
  Occurrence of similar sequences in the 3 major peanut allergens accounts for the high extent of cross-reactivity among them.
authors: Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria. merima.bublin@meduniwien.ac.at
authors: Merima
authors: M
authors: Bublin
authors: Maria
authors: M
authors: Kostadinova
authors: Christian
authors: C
authors: Radauer
authors: Christine
authors: C
authors: Hafner
authors: Zsolt
authors: Z
authors: Szépfalusi
authors: Eva-Maria
authors: EM
authors: Varga
authors: Soheila J
authors: SJ
authors: Maleki
authors: Karin
authors: K
authors: Hoffmann-Sommergruber
authors: Heimo
authors: H
authors: Breiteneder
mesh_terms: D055516:2S Albumins, Plant / Q000276:immunology*; D000595:Amino Acid Sequence; D052179:Antigens, Plant / Q000276:immunology*; D003429:Cross Reactions; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000276:immunology*; D055314:Seed Storage Proteins / Q000276:immunology*
chemical_list: D055516:2S Albumins, Plant; D052179:Antigens, Plant; C500889:Ara h 1 protein, Arachis hypogaea; C078642:Ara h II protein, Arachis hypogaea; D006023:Glycoproteins; D008565:Membrane Proteins; D010940:Plant Proteins; D055314:Seed Storage Proteins; C118207:allergen Ara h3; D007073:Immunoglobulin E