title: IgE versus IgG4 epitopes of the peanut allergen Ara h 1 in patients with severe allergy.
abstract: BACKGROUND
  Development and maintenance of tolerance to food allergens appears to be associated with alterations in antigen specific IgE and IgG4 responses. Previous studies have focused only on comparing IgE and IgG4 linear epitope recognition patterns but take no account of conformational epitopes.
  
  
  OBJECTIVE
  The aim of this study was to compare Ara h 1-specific IgE and IgG4 epitope recognition patterns in patients with severe peanut allergy, applying a method allowing for identification of both linear and conformational epitopes.
  
  
  METHODS
  Polyclonal sera from three individual patients, suffering from severe allergic reaction to peanuts, including anaphylaxis, were used to analyse the IgE and IgG4 epitope recognition patterns of the major peanut allergen Ara h 1. Epitope identification was conducted by competitive immuno-screening of a phage-displayed random heptamer peptide library. Resulting epitope-mimicking sequences were aligned for identification of consensus sequences and localised on the surface of the Ara h 1 molecule by a computer-based algorithm.
  
  
  RESULTS
  All epitope-mimicking sequences identified were found to correspond to conformational epitopes. Each individual patient had his/her own distinct IgE as well as IgG4 epitope recognition profile, though some important IgE epitopes were common to all patients. In general the IgG4 epitope pattern was more heterogeneous than the IgE pattern, did not coincide with IgE epitopes and had a lower affinity than IgE.
  
  
  CONCLUSIONS
  This study demonstrated the usefulness of the phage-display technology in distinguishing between the epitope pattern of IgE and IgG4, giving detailed information on fine specificity and affinity. Competitive immuno-screening of phage-display random peptide libraries could be a future valuable tool to study the balance and dynamics of the IgE and IgG4 epitope recognition repertoire and provide a diagnostic tool giving information on the associated allergic phenotype.
authors.affiliation: National Food Institute, Division of Toxicology and Risk Assessment, Technical University of Denmark, Søborg, Denmark. Electronic address: kalb@food.dtu.dk.
authors.forename: K L
authors.initials: KL
authors.lastname: Bøgh
authors.affiliation: Novozymes, Department of Protein Screening, Bagsværd, Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Nielsen
authors.affiliation: Medical University of Vienna, Department of Paediatrics, Vienna, Austria.
authors.forename: T
authors.initials: T
authors.lastname: Eiwegger
authors.affiliation: National Food Institute, Division of Toxicology and Risk Assessment, Technical University of Denmark, Søborg, Denmark.
authors.forename: C B
authors.initials: CB
authors.lastname: Madsen
authors.affiliation: Institute of Food Research, Food and Health, Norwich, United Kingdom.
authors.forename: E N C
authors.initials: EN
authors.lastname: Mills
authors.affiliation: Institute of Food Research, Food and Health, Norwich, United Kingdom.
authors.forename: N M
authors.initials: NM
authors.lastname: Rigby
authors.affiliation: Medical University of Vienna, Department of Paediatrics, Vienna, Austria.
authors.forename: Z
authors.initials: Z
authors.lastname: Szépfalusi
authors.affiliation: Novozymes, Department of Protein Screening, Bagsværd, Denmark.
authors.forename: E L
authors.initials: EL
authors.lastname: Roggen
mesh_terms: D000595:Amino Acid Sequence; D052179:Antigens, Plant / Q000737:chemistry / Q000276:immunology*; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D006023:Glycoproteins / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D008565:Membrane Proteins; D018716:Molecular Mimicry; D021183:Peanut Hypersensitivity / Q000276:immunology*; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology*; D016415:Sequence Alignment
chemical_list: D052179:Antigens, Plant; C500889:Ara h 1 protein, Arachis hypogaea; D000939:Epitopes; D006023:Glycoproteins; D007074:Immunoglobulin G; D008565:Membrane Proteins; D010940:Plant Proteins; D007073:Immunoglobulin E
keywords: Ara h 1; ETM; Epitopes; IgE; IgG4; PBS; Peanut allergy; Phage-display; RT; SMP; epitope mapping tool; phosphate buffer saline; room temperature; skimmed milk powder