title: Molecular, structural, and immunologic relationships between different families of recombinant calcium-binding pollen allergens.
abstract: BACKGROUND
  Calcium-binding plant allergens can be grouped in different families according to the number of calcium-binding domains (EF hands).
  
  
  OBJECTIVE
  We sought to identify pollens containing crossreactive calcium-binding allergens and to investigate structural and immunologic similarities of members belonging to different families of calcium-binding allergens.
  
  
  METHODS
  By means of multiple sequence alignment and molecular modeling, we searched for structural similarities among pollen allergens with 2 (Phl p 7, timothy grass; Aln g 4, alder), 3 (Bet v 3, birch) and 4 EF hands (Jun o 4, prickly juniper). Purified recombinant Aln g 4 and Jun o 4 were used to determine the prevalence of IgE recognition in 210 patients sensitized to different pollens and to search, by means of ELISA competition, for the presence of cross-reactive epitopes in pollens from 16 unrelated plant species. IgE cross-reactivity among the allergen families was studied with purified rPhl p 7, rAln g 4, rBet v 3, and rJun o 4 and 2 synthetic peptides comprising the N-terminal and C-terminal EF hands of Phl p 7 by means of ELISA competition.
  
  
  RESULTS
  Structural similarities were found by using molecular modeling among the allergens with 2, 3, and 4 EF hands. Pollens from 16 unrelated plants contained Aln g 4- and Jun o 4-related epitopes. Twenty-two percent of the patients with multiple pollen sensitization reacted to at least one of the calcium-binding allergens. A hierarchy of IgE cross-reactivity (rPhl p7 > rAln g 4 > rJun o 4 > rBet v 3) could be established that identified rPhl p 7 as the EF-hand allergen containing most IgE epitopes in the population studied.
  
  
  CONCLUSIONS
  The demonstration that members of different families of calcium-binding plant allergens share similarities suggests that it may be possible to use representative molecules for the diagnosis and therapy of allergies to EF-hand allergens.
authors.affiliation: Department of Immunology, Istituto Superiore di Sanità, Rome.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Tinghino
authors.forename: Anna
authors.initials: A
authors.lastname: Twardosz
authors.forename: Bianca
authors.initials: B
authors.lastname: Barletta
authors.forename: Eleonora M r
authors.initials: EM
authors.lastname: Puggioni
authors.forename: Patrizia
authors.initials: P
authors.lastname: Iacovacci
authors.forename: Cinzia
authors.initials: C
authors.lastname: Butteroni
authors.forename: Claudia
authors.initials: C
authors.lastname: Afferni
authors.forename: Adriano
authors.initials: A
authors.lastname: Mari
authors.forename: Brigitte
authors.initials: B
authors.lastname: Hayek
authors.forename: Gabriella
authors.initials: G
authors.lastname: Di Felice
authors.forename: Margarete
authors.initials: M
authors.lastname: Focke
authors.forename: Kerstin
authors.initials: K
authors.lastname: Westritschnig
authors.forename: Rudolf
authors.initials: R
authors.lastname: Valenta
authors.forename: Carlo
authors.initials: C
authors.lastname: Pini
mesh_terms: D000485:Allergens / Q000009:adverse effects / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology*; D007073:Immunoglobulin E / Q000097:blood; D008958:Models, Molecular; D008969:Molecular Sequence Data; D006109:Poaceae / Q000009:adverse effects / Q000276:immunology*; D011058:Pollen / Q000009:adverse effects / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D014197:Trees / Q000009:adverse effects / Q000276:immunology*
chemical_list: D000485:Allergens; D011994:Recombinant Proteins; D007073:Immunoglobulin E; D002118:Calcium