title: The value of specific IgE to peanut and its component Ara h 2 in the diagnosis of peanut allergy.
abstract: BACKGROUND
  To avoid unnecessary oral food challenges, which are time consuming, stressful, and risky, improved in vitro diagnostic methods for food allergy such as component resolved diagnostics are still under investigation.
  
  
  OBJECTIVE
  To investigate the role of whole peanut- and peanut-component (Ara h 1, Ara h 2, Ara h 3, Ara h 6 and Ara h 8)-specific IgE levels in the diagnostic procedure of peanut allergy as well as the diagnostic properties of peanut-specific IgG and IgG4.
  
  
  METHODS
  Sixty-one children underwent oral peanut challenge tests for diagnostic purposes irrespective of their peanut-specific IgE levels. Peanut-specific serum IgE, IgG, and IgG4 levels were determined by ImmunoCAP FEIA and specific IgE against individual peanut proteins by Immuno Solid-phase Allergen Chip.
  
  
  RESULTS
  Thirty-four of 61 patients (56%) had a peanut allergy. No significant difference was observed for peanut-specific IgG or peanut-specific IgG4 levels between patients who were allergic and tolerant patients, whereas peanut-specific IgE was significant higher in patients who were allergic than in tolerant patients (P < .005). Twenty-five of 61 children had peanut-specific IgE above a previously proposed cutoff level of 15 kUA/L; however, 7 of these 25 children (28%) were clinically tolerant. Ara h 2-specific IgE was significantly lower in tolerant than in patients with allergies (P < .0001). Interestingly, 94% of the patients with peanut allergies showed IgE-binding to Ara h 2. Unfortunately, 26% of the sensitized but tolerant patients have shown IgE binding to Ara h 2 too.
  
  
  CONCLUSIONS
  Neither the level of specific IgE to peanut nor to Ara h 2 was able to clearly distinguish patients with clinical relevant peanut allergy from those who were clinical tolerant in our population. As expected, peanut-specific IgG and IgG4 did not improve the diagnostic procedure.
authors.affiliation: Department of Pediatric Pneumology and Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany; Division of Allergy and Clinical Immunology, Department of Pediatrics, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Lucila C
authors.initials: LC
authors.lastname: Lopes de Oliveira
authors.affiliation: Department of Pediatric Pneumology and Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Aderhold
authors.affiliation: VBC Genomics, Vienna, Austria.
authors.forename: Marianne
authors.initials: M
authors.lastname: Brill
authors.affiliation: Department of Pediatric Pneumology and Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Schulz
authors.affiliation: Department of Pediatric Pneumology and Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Rolinck-Werninghaus
authors.affiliation: Institute of Food Research, Norwich, United Kingdom.
authors.forename: E N
authors.initials: EN
authors.lastname: Clare Mills
authors.affiliation: Department of Pediatric Pneumology and Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany; Pediatric Allergology and Pneumology, German Red Cross Hospital Westend, Berlin, Germany.
authors.forename: Bodo
authors.initials: B
authors.lastname: Niggemann
authors.affiliation: Division of Allergy and Clinical Immunology, Department of Pediatrics, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Charles Kirov
authors.initials: CK
authors.lastname: Naspitz
authors.affiliation: Department of Pediatric Pneumology and Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wahn
authors.affiliation: Department of Pediatric Pneumology and Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany. Electronic address: kirsten.beyer@charite.de.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Beyer
mesh_terms: D055516:2S Albumins, Plant / Q000276:immunology*; D000293:Adolescent; D052179:Antigens, Plant / Q000276:immunology*; D010367:Arachis / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D008297:Male; D021183:Peanut Hypersensitivity / Q000175:diagnosis*
chemical_list: D055516:2S Albumins, Plant; D052179:Antigens, Plant; C500890:Ara h 2 allergen, Arachis hypogaea; D006023:Glycoproteins; D007074:Immunoglobulin G; D007073:Immunoglobulin E
keywords: Ara h 1; Ara h 3; Ara h 6; Ara h 8; Ara h 2; Component-resolved diagnostics; IgE; IgG; IgG(4); Immuno Solid-phase Allergen Chip; Peanut allergy