title: Walnut allergy in peanut-allergic patients: significance of sequential epitopes of walnut homologous to linear epitopes of Ara h 1, 2 and 3 in relation to clinical reactivity.
abstract: BACKGROUND
  Peanut allergy is a frequent and potentially life-threatening food allergy. Despite the large taxonomic distance between the plants, peanut-allergic patients often react to tree nuts such as walnuts. While the allergens of peanut and walnut have a high degree of homology in their amino-acid sequences, it is unknown whether this similarity is responsible for the observed co-reactivity. Therefore, we analyzed the binding of specific IgE antibodies to sequential epitopes of peanut and walnut in peanut-allergic patients with and without walnut allergy.
  
  
  METHODS
  The IgE binding to previously described sequential epitopes of peanut and the homologous regions of walnut was assessed in 32 peanut-allergic patients using a peptide microarray technology. Twelve patients had a clinically relevant walnut allergy and 20 were tolerant to walnut. Inhibition assays with peanut peptides and corresponding walnut sequences were performed to show specific binding to sequential epitopes.
  
  
  RESULTS
  No differences in the recognition of sequential epitopes could be found between peanut-allergic patients with or without walnut allergy. Only a few patients showed IgE binding to walnut sequences that corresponded to sequential epitopes of peanut. In the inhibition assays, no relevant cross-reacting IgE antibodies could be detected for the peptides analyzed.
  
  
  CONCLUSIONS
  Our results indicate that although they share a rather high degree of homology with the corresponding regions of walnut allergens, the sequence stretches previously identified as sequential IgE binding epitopes of Ara h 1, Ara h 2 and Ara h 3 have no IgE binding equivalents in walnut allergens.
authors: Department of Pediatric Pneumology and Immunology, University Children's Hospital Charité, Berlin, Germany.
authors: Leonard
authors: L
authors: Rosenfeld
authors: Wayne
authors: W
authors: Shreffler
authors: Ludmilla
authors: L
authors: Bardina
authors: Bodo
authors: B
authors: Niggemann
authors: Ulrich
authors: U
authors: Wahn
authors: Hugh A
authors: HA
authors: Sampson
authors: Kirsten
authors: K
authors: Beyer
mesh_terms: D055516:2S Albumins, Plant / Q000737:chemistry / Q000276:immunology; D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D052179:Antigens, Plant / Q000737:chemistry / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry / Q000276:immunology*; D006023:Glycoproteins / Q000737:chemistry / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D031324:Juglans / Q000276:immunology*; D008565:Membrane Proteins; D021184:Nut Hypersensitivity / Q000150:complications / Q000276:immunology*; D021183:Peanut Hypersensitivity / Q000150:complications / Q000276:immunology*; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology; D040081:Protein Array Analysis; 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; C549941:Ara h 3 allergen, Arachis hypogea; D000939:Epitopes; D006023:Glycoproteins; C515172:Jug r 4 allergen; D008565:Membrane Proteins; D010940:Plant Proteins; D007073:Immunoglobulin E