Food, drug, insect sting allergy, and anaphylaxis
Component-resolved diagnosis of baker's allergy based on specific IgE to recombinant wheat flour proteins

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Background

Sensitization to wheat flour plays an important role in the development and diagnosis of baker's asthma.

Objectives

We evaluated wheat allergen components as sensitizers for bakers with work-related complaints, with consideration of cross-reactivity to grass pollen.

Methods

Nineteen recombinant wheat flour proteins and 2 cross-reactive carbohydrate determinants were tested by using CAP-FEIA in sera of 101 bakers with wheat flour allergy (40 German, 37 Dutch, and 24 Spanish) and 29 pollen-sensitized control subjects with wheat-specific IgE but without occupational exposure. IgE binding to the single components was inhibited with wheat flour, rye flour, and grass pollen. The diagnostic efficiencies of IgE tests with single allergens and combinations were evaluated by assessing their ability to discriminate between patients with baker's allergy and control subjects based on receiver operating characteristic analyses.

Results

Eighty percent of bakers had specific IgE levels of 0.35 kUA/L or greater and 91% had specific IgE levels of 0.1 kUA/L or greater to at least one of the 21 allergens. The highest frequencies of IgE binding were found for thiol reductase (Tri a 27) and the wheat dimeric α-amylase inhibitor 0.19 (Tri a 28). Cross-reactivity to grass pollen was proved for 9 components, and cross-reactivity to rye flour was proved for 18 components. A combination of IgE tests to 5 components, Tri a 27, Tri a 28, tetrameric α-amylase inhibitor CM2 (Tri a 29.02), serine protease inhibitor–like allergen (Tri a 39), and 1-cys-peroxiredoxin (Tri a 32), produced the maximal area under the curve (AUC = 0.84) in receiver operating characteristic analyses, but this was still lower than the AUC for wheat- or rye flour–specific IgE (AUC = 0.89 or 0.88, respectively).

Conclusions

Component-resolved diagnostics help to distinguish between sensitization caused by occupational flour exposure and wheat seropositivity based on cross-reactivity to grass pollen. For routine diagnosis of baker's allergy, however, allergen-specific IgE tests with whole wheat and rye flour extracts remain mandatory because of superior diagnostic sensitivity.

Section snippets

Patients and sera

The 40 German bakers with work-related complaints were the same as described previously9 and were selected based on physician-diagnosed occupational disease and wheat allergy. The 24 Spanish bakers had work-related asthma and rhinitis and a positive inhalation challenge test result to wheat or rye flour. All consecutive bakers attending La Paz Hospital in 2005 to 2008 who were given a diagnosis of baker's asthma caused by wheat flour were selected. The 37 Dutch bakers were selected during the

Results

Of 101 bakers with work-related asthma, rhinitis and wheat flour sensitization, or both, 86 also had increased total IgE concentrations (>100 kUA/L), all had sIgE to rye flour, and 75 had sIgE to grass pollen (Fig 1). Bakers from the different countries were not significantly different concerning age or total and sIgE levels to wheat and rye flour or grass pollen. The same was true for control subjects from the different countries. Control subjects had significantly higher sIgE values to grass

Discussion

Several single wheat flour allergens relevant to baker's asthma have been identified in the last 30 years, and a number of them have been characterized on a molecular level. The current allergen nomenclature list of the World Health Organization/International Union of Immunological Societies comprises 20 wheat allergens (www.allergen.org). The Triticum aestivum allergen numbers start with Tri a 12 (profilin) and end with Tri a 39 (SPILA), leaving a place for wheat pollen allergens homologous to

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  • Cited by (0)

    Supported by the DGUV (German Social Accident Insurance).

    Disclosure of potential conflict of interest: H.-P. Rihs delivered recombinant wheat proteins to EUROIMMUN AG for testing the effects in their diagnostic system and will receive nonstatutory stock options due in 2016 for his work as a Scientific Advisory Board Member for Yulex Corporation, Phoenix, Arizona. The rest of the authors declare that they have no relevant conflicts of interest.

    Allergen names, including isoallergen and variant numbers, used in this study were approved by the International Union of Immunological Societies (IUIS) Allergen Nomenclature Sub-Committee.

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