title: Moving from peanut extract to peanut components: towards validation of component-resolved IgE tests.
abstract: BACKGROUND
  Replacement of peanut extracts by recombinant peanut components is an important step in allergy serologic testing. Criteria are needed for the unbiased inclusion of patients into a study to validate such a replacement.
  
  
  METHODS
  Plasma samples from 64 peanut-positive children (42 reactors, 22 nonreactors in a double-blind, placebo-controlled food challenge) were used to compare IgE reactivity to six recombinant peanut allergens with reactivity to natural peanut proteins extracted at neutral or low pH. We tested the hypothesis that poor extractability of Ara h 9 and other basic allergens at neutral pH leads to under-representation of patients with such sensitization.
  
  
  RESULTS
  IgE reactivity to the components did not fully explain IgE reactivity to peanut extract in 5 of 32 reactors with IgE to peanut extract ≤100 kUA /l. IgE reactivity to components was stronger than to the extract in 11 plasma samples, which was largely due to a low Ara h 8 reactivity of the extract. IgE reactivity to Ara h 9 was much lower than reactivity to other basic proteins, some of which bound IgE well in the RAST, but lost IgE reactivity upon immunoblotting.
  
  
  CONCLUSIONS
  Conventional peanut extracts are deficient in significant IgE-binding components. The inclusion of patients for a validation study should be based on serology performed with improved peanut reagents to avoid a bias against these under-represented, potentially important allergens. To judge clinical relevance of an allergen, the reagent used for inclusion of patients needs to be efficient in detecting IgE to this component.
authors.affiliation: Sanquin Blood Supply Foundation and Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: J A
authors.initials: JA
authors.lastname: Aalberse
authors.forename: Y
authors.initials: Y
authors.lastname: Meijer
authors.forename: N
authors.initials: N
authors.lastname: Derksen
authors.forename: T
authors.initials: T
authors.lastname: van der Palen-Merkus
authors.forename: E
authors.initials: E
authors.lastname: Knol
authors.forename: R C
authors.initials: RC
authors.lastname: Aalberse
mesh_terms: D000485:Allergens / Q000276:immunology; D052179:Antigens, Plant / Q000276:immunology; D010367:Arachis / Q000276:immunology*; D015415:Biomarkers / Q000097:blood; D002648:Child; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000097:blood*; D021183:Peanut Hypersensitivity / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D010936:Plant Extracts / Q000276:immunology; D014674:Plant Proteins, Dietary / Q000276:immunology
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D015415:Biomarkers; D010936:Plant Extracts; D014674:Plant Proteins, Dietary; D007073:Immunoglobulin E