title: Diagnostic Value of Antigen-Specific Immunoglobulin E Immunoassays against Ara h 2 and Ara h 8 Peanut Components in Child Food Allergy.
abstract: BACKGROUND
  Peanut allergy is one of the most severe food allergies in children. The diagnostic gold standard is the oral food challenge (OFC). However, OFC has inherent risks and is time consuming. The measurement of specific immunoglobulin E (sIgE) to peanut components in blood detects peanut sensitization, but the decision point predicting allergy is still unclear. The aim of this study was to determine the diagnostic value of these tests for the evaluation of child peanut allergy.
  
  
  METHODS
  In this retrospective study, 81 children were referred for peanut allergy. The diagnosis of peanut allergy was based on the clinical context and a positive OFC. Levels of sIgE against whole peanuts or peanut components (Ara h 2 and Ara h 8) were determined by immunoassay.
  
  
  RESULTS
  The Ara h 2 sIgE assay has the best negative predictive value (0.93) and positive predictive value (1) at a cutoff of 0.1 kU/l. Ara h 2 sIgE titers can predict the risk of anaphylaxis (<0.44 kU/l, low risk; >14 kU/l, high risk). The Ara h 8 sIgE assay is not able to discriminate peanut-allergic patients but can be used to evaluate possible cross-reactions to birch pollen with a low risk of anaphylaxis. The best diagnostic strategy is to first determine the Ara h 2 sIgE level and, if negative, evaluate Ara h 8 sIgE.
  
  
  CONCLUSIONS
  We propose an algorithm for a better use of peanut component sIgE immunoassays that should improve their diagnostic value and avoid unnecessary OFC.
authors.affiliation: Department of Immunology, Rouen University Hospital, Rouen, France.
authors.forename: Jérémie
authors.initials: J
authors.lastname: Martinet
authors.forename: Laure
authors.initials: L
authors.lastname: Couderc
authors.forename: Florian
authors.initials: F
authors.lastname: Renosi
authors.forename: Victor
authors.initials: V
authors.lastname: Bobée
authors.forename: Christophe
authors.initials: C
authors.lastname: Marguet
authors.forename: Olivier
authors.initials: O
authors.lastname: Boyer
mesh_terms: D055516:2S Albumins, Plant / Q000276:immunology*; D000465:Algorithms; D000918:Antibody Specificity / Q000276:immunology; D052179:Antigens, Plant / Q000276:immunology*; D001249:Asthma / Q000097:blood / Q000175:diagnosis / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D003429:Cross Reactions / Q000276:immunology; D005260:Female; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology*; D008297:Male; D021183:Peanut Hypersensitivity / Q000097:blood / Q000175:diagnosis* / Q000276:immunology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D055516:2S Albumins, Plant; D052179:Antigens, Plant; C500890:Ara h 2 allergen, Arachis hypogaea; C000594056:Ara h 8 allergen, peanut; D006023:Glycoproteins; D007073:Immunoglobulin E