title: Type I allergy to elderberry (Sambucus nigra) is elicited by a 33.2 kDa allergen with significant homology to ribosomal inactivating proteins.
abstract: BACKGROUND
  Patients suffering from allergic rhinoconjunctivitis and dyspnoea during summer may exhibit these symptoms after contact with flowers or dietary products of the elderberry tree Sambucus nigra.
  
  
  OBJECTIVE
  Patients with a history of summer hayfever were tested in a routine setting for sensitization to elderberry. Nine patients having allergic symptoms due to elderberry and specific sensitization were investigated in detail. We studied the responsible allergens in extracts from elderberry pollen, flowers and berries, and investigated cross-reactivity with allergens from birch, grass and mugwort.
  
  
  METHODS
  Sera from patients were tested for IgE reactivity to elderberry proteins by one-dimensional (1D) and 2D electrophoresis/immunoblotting. Inhibition studies with defined allergens and elderberry-specific antibodies were used to evaluate cross-reactivity. The main elderberry allergen was purified by gel filtration and reversed-phase HPLC, and subjected to mass spectrometry. The in-gel-digested allergen was analysed by the MS/MS sequence analysis and peptide mapping. The N-terminal sequence of the predominant allergen was analysed.
  
  
  RESULTS
  0.6% of 3668 randomly tested patients showed positive skin prick test and/or RAST to elderberry. IgE in patients' sera detected a predominant allergen of 33.2 kDa in extracts from elderberry pollen, flowers and berries, with an isoelectric point at pH 7.0. Pre-incubation of sera with extracts from birch, mugwort or grass pollen rendered insignificant or no inhibition of IgE binding to blotted elderberry proteins. Specific mouse antisera reacted exclusively with proteins from elderberry. N-terminal sequence analysis, as well as MS/MS spectrometry of the purified elderberry allergen, indicated homology with ribosomal inactivating proteins (RIPs).
  
  
  CONCLUSIONS
  We present evidence that the elderberry plant S. nigra harbours allergenic potency. Independent methodologies argue for a significant homology of the predominant 33.2 kDa elderberry allergen with homology to RIPs. We conclude that this protein is a candidate for a major elderberry allergen with designation Sam n 1.
authors.affiliation: Department of Pediatrics and Juvenile Medicine, University of Vienna Medical School, Vienna, Austria.
authors.forename: E
authors.initials: E
authors.lastname: Förster-Waldl
authors.forename: M
authors.initials: M
authors.lastname: Marchetti
authors.forename: I
authors.initials: I
authors.lastname: Schöll
authors.forename: M
authors.initials: M
authors.lastname: Focke
authors.forename: C
authors.initials: C
authors.lastname: Radauer
authors.forename: T
authors.initials: T
authors.lastname: Kinaciyan
authors.forename: I
authors.initials: I
authors.lastname: Nentwich
authors.forename: S
authors.initials: S
authors.lastname: Jäger
authors.forename: E R
authors.initials: ER
authors.lastname: Schmid
authors.forename: G
authors.initials: G
authors.lastname: Boltz-Nitulescu
authors.forename: O
authors.initials: O
authors.lastname: Scheiner
authors.forename: E
authors.initials: E
authors.lastname: Jensen-Jarolim
mesh_terms: D000485:Allergens / Q000032:analysis* / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D003429:Cross Reactions; D035264:Flowers; D005638:Fruit; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000209:etiology* / Q000276:immunology; D007073:Immunoglobulin E / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000235:genetics; D010936:Plant Extracts / Q000737:chemistry* / Q000276:immunology; D010940:Plant Proteins / Q000235:genetics; D011058:Pollen; D054790:Ribosome Inactivating Proteins, Type 2; D027924:Sambucus nigra / Q000276:immunology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D000485:Allergens; D010936:Plant Extracts; D010940:Plant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D007073:Immunoglobulin E; D009699:N-Glycosyl Hydrolases