title: IgE antibodies of fish allergic patients cross-react with frog parvalbumin.
abstract: BACKGROUND
  The major allergens in fish are parvalbumins. Important immunoglobulin (Ig)E cross-recognition of parvalbumins from different fish species has been shown. Recently frog parvalbumin alpha has been found to be responsible for a case of IgE-mediated anaphylaxis triggered by the ingestion of frog meat. The aim of this study was to investigate whether IgE antibodies of fish allergic persons cross-react with frog parvalbumin and to appreciate its clinical relevance.
  
  
  METHODS
  The sera of 15 fish allergic patients and one fish and frog allergic patient were tested by IgE-immunoblotting against frog muscle extract. Sera were tested against recombinant parvalbumin alpha and beta from Rana esculenta. Skin prick tests were performed in selected patients with recombinant frog parvalbumin. Ca(2+) depletion experiments and inhibition studies with purified cod and frog recombinant parvalbumin were done to characterize the cross-reactive pattern.
  
  
  RESULTS
  Fourteen of the sera tested had IgE antibodies recognizing low molecular weight components in frog muscle extract. Calcium depletion experiments or inhibition of patient sera with purified cod parvalbumin led to a significant or complete decrease in IgE binding. When tested against recombinant parvalbumins, three of 13 sera reacted with alpha parvalbumin and 11 of 12 reacted with beta parvalbumin from R. esculenta. Skin prick tests performed with recombinant frog parvalbumin were positive in fish allergic patients. Inhibition studies showed that a fish and frog allergic patient was primarily sensitized to fish parvalbumin.
  
  
  CONCLUSIONS
  Cod parvalbumin, a major cross-reactive allergen among different fish species, shares IgE binding epitopes with frog parvalbumin. This in vitro cross-reactivity seems to be also clinically relevant. Parvalbumins probably represent a new family of cross-reactive allergens.
authors.affiliation: Unit of Immunology and Allergology, Centre Hospitalier de Luxembourg, 4 rue Barblé, L-1210 Luxembourg.
authors.forename: C
authors.initials: C
authors.lastname: Hilger
authors.forename: L
authors.initials: L
authors.lastname: Thill
authors.forename: F
authors.initials: F
authors.lastname: Grigioni
authors.forename: C
authors.initials: C
authors.lastname: Lehners
authors.forename: P
authors.initials: P
authors.lastname: Falagiani
authors.forename: A
authors.initials: A
authors.lastname: Ferrara
authors.forename: C
authors.initials: C
authors.lastname: Romano
authors.forename: W
authors.initials: W
authors.lastname: Stevens
authors.forename: F
authors.initials: F
authors.lastname: Hentges
mesh_terms: D000818:Animals; D001001:Anura / Q000276:immunology*; D003429:Cross Reactions / Q000276:immunology*; D005399:Fishes / Q000276:immunology; D005512:Food Hypersensitivity / Q000097:blood / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology*; D010320:Parvalbumins / Q000276:immunology*; D017747:Seafood / Q000009:adverse effects*
chemical_list: D010320:Parvalbumins; D007073:Immunoglobulin E