Wheat IgE-Mediated Food Allergy in European Patients: α-Amylase Inhibitors, Lipid Transfer Proteins and Low-Molecular-Weight Glutenins

Abstract

Background: Three main problems hamper the identification of wheat food allergens: (1) lack of a standardized procedure for extracting all of the wheat protein fractions; (2) absence of double-blind, placebo-controlled food challenge studies that compare the allergenic profile of Osborne’s three protein fractions in subjects with real wheat allergy, and (3) lack of data on the differences in IgE-binding capacity between raw and cooked wheat. Methods: Sera of 16 wheat-challenge-positive patients and 6 patients with wheat anaphylaxis, recruited from Italy, Denmark and Switzerland, were used for sodium dodecyl sulfate-polyacrylamide gel electrophoresis/immunoblotting of the three Osborne’s protein fractions (albumin/globulin, gliadins and glutenins) of raw and cooked wheat. Thermal sensitivity of wheat lipid transfer protein (LTP) was investigated by spectroscopic approaches. IgE cross-reactivity between wheat and grass pollen was studied by blot inhibition. Results: The most important wheat allergens were the α-amylase/trypsin inhibitor subunits, which were present in all three protein fractions of raw and cooked wheat. Other important allergens were a 9-kDa LTP in the albumin/globulin fraction and several low-molecular-weight (LMW) glutenin subunits in the gluten fraction. All these allergens showed heat resistance and lack of cross-reactivity to grass pollen allergens. LTP was a major allergen only in Italian patients. Conclusions: The α-amylase inhibitor was confirmed to be the most important wheat allergen in food allergy and to play a role in wheat-dependent exercise-induced anaphylaxis, too. Other important allergens were LTP and the LMW glutenin subunits.

Analysis of Food Allergen Structures and Development of Foods for Allergic Patients

“…[14][15][16][17] Later, several groups identified wheat allergens. [18][19][20][21] The proteins responsible for wheat-induced atopic dermatitis are described below in section 2.…”

“…Recombinant low-molecular-weight glutenins with many Gln-Gln-Gln-Pro-Pro motifs have been expressed in Escherichia coli by a pET vector system, and were confirmed to possess IgE-binding ability. 29) As other allergens, thioredoxin, 19) lipid transfer protein, 20) acyl-CoA oxidase, 30) peroxidase, 31) and fructose-bisphosphate aldolase 32) were identified. 8,21) In addition, the epitope structures of gliadin in patients with FDEIA 24) and celiac disease 33) have been recently reported.…”

“…In addition, amylase inhibitors cannot be used due to their allergenic potencies. 12,20) As a result of enzyme screening, bromelain and actinase showed high ability to hydrolyze peptide bonds near the proline residues with low amylase activities, [34][35][36][37] but some patients were also sensitive to bromelain itself. 38) Hence, actinase was selected to produce hypoallergenic flour.…”

A Baker with Asthma and Wheat Flour Food Allergy

“…More than 100 IgE-binding protein spots have been detected in wheat flour and sera from sensitized bakers show not only reactions to many of these antigens but also considerable variability in individual sensitization patterns (2). A wide array of wheat flour proteins, both salt-soluble proteins and prolamins, and particularly members of the α-amylase inhibitor family and ω5-gliadin (in wheat-dependent exercise-induced anaphylaxis), have been linked to food wheat allergy (2)(3)(4). LTPs have (wheat flour Tri a 14) recently been identified as a relevant allergen associated with both baker's asthma and wheat IgE-mediated food allergy (3)(4)(5)(6).…”

“…A wide array of wheat flour proteins, both salt-soluble proteins and prolamins, and particularly members of the α-amylase inhibitor family and ω5-gliadin (in wheat-dependent exercise-induced anaphylaxis), have been linked to food wheat allergy (2)(3)(4). LTPs have (wheat flour Tri a 14) recently been identified as a relevant allergen associated with both baker's asthma and wheat IgE-mediated food allergy (3)(4)(5)(6). Several of the major salt-insoluble wheat flour proteins (prolamins) such as gliadin also appear to be implicated in baker's asthma and wheat mediated food allergy (7).…”