title: IgE binding to pepsin-digested food extracts.
abstract: BACKGROUND
  Pepsin resistance of allergens like lipid transfer protein and 2S albumin has been suggested as explanation for the severity of symptoms often induced by these allergens. Component-resolved diagnosis with purified labile and stable allergens has therefore been proposed to better characterize the risk involved in a positive in vitro IgE test. However, for many foods, purified allergens are not (yet) available.
  
  
  OBJECTIVE
  It was the aim of this study to evaluate the potential of pepsin-digested whole-food extracts to distinguish between IgE responses to stable (potentially severe) and labile (mild) allergens.
  
  
  METHODS
  Sera (n = 143) from Italian, Spanish and Dutch patients with hazelnut and/or apple ingestion-related symptoms were analyzed for residual IgE binding to pepsin-resistant hazelnut and/or apple allergens. Control and pepsin-digested hazelnut and apple extracts were used for radioallergosorbent test analysis and immunoblot analysis.
  
  
  RESULTS
  Pepsin digestion of food extracts, like from hazelnut and apple used for in vitro diagnostic tests, provides a way to distinguish sensitization to pepsin-resistant allergens from that to pepsin-susceptible allergens. In this selected group of patients, IgE reactivity to pepsin-digested extracts correlated with sensitization to the stable allergen lipid transfer protein. The analysis further revealed that the use of soluble pepsin can result in false-positive in vitro tests (2/143).
  
  
  CONCLUSIONS
  Pepsin-digested food extracts are a convenient tool to identify patients with IgE antibodies against potentially dangerous stable allergens, in particular for those foods where the relevant stable allergens have not yet been identified. This can increase the clinical prognostic value of food allergy serology.
authors.affiliation: Sanquin Research, Department of Immunopathology and Laboratory for Experimental and Clinical Immunology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Jaap H
authors.initials: JH
authors.lastname: Akkerdaas
authors.forename: Marjolein
authors.initials: M
authors.lastname: Wensing
authors.forename: Riccardo
authors.initials: R
authors.lastname: Asero
authors.forename: Montserrat
authors.initials: M
authors.lastname: Fernandez Rivas
authors.forename: Montserrat Fernandez
authors.initials: MF
authors.lastname: Rivas
authors.forename: André C
authors.initials: AC
authors.lastname: Knulst
authors.forename: Suzanne
authors.initials: S
authors.lastname: Bolhaar
authors.forename: Susan L
authors.initials: SL
authors.lastname: Hefle
authors.forename: Rob C
authors.initials: RC
authors.lastname: Aalberse
authors.forename: Ronald
authors.initials: R
authors.lastname: van Ree
mesh_terms: D000485:Allergens / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D005512:Food Hypersensitivity / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D027845:Malus / Q000276:immunology*; D021184:Nut Hypersensitivity / Q000276:immunology*; D009754:Nuts / Q000276:immunology*; D010434:Pepsin A / Q000378:metabolism*; D011852:Radioallergosorbent Test
chemical_list: D000485:Allergens; D007073:Immunoglobulin E; D010434:Pepsin A