IgE binding to pepsin-digested food extracts.
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.
Akkerdaas
Jaap H
JH
Sanquin Research, Department of Immunopathology and Laboratory for Experimental and Clinical Immunology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
Wensing
Marjolein
M
Asero
Riccardo
R
Fernandez Rivas
Montserrat
M
Rivas
Montserrat Fernandez
MF
Knulst
André C
AC
Bolhaar
Suzanne
S
Hefle
Susan L
SL
Aalberse
Rob C
RC
van Ree
Ronald
R
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
D000485:Allergens; D007073:Immunoglobulin E; D010434:Pepsin A