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.
Background: The roles played by different peach allergens with respect to symptom severity have not been completely ascertained. We have evaluated the diagnostic efficacy of peach recombinant allergens ImmunoCAP compared to peach in the identification of subjects at an increased risk for severe reactions to peaches. Methods: 148 peach-allergic patients were divided based on their symptom severity into 2 groups: mild oral allergy syndrome (OAS) and severe OAS. Anti-rPru p 1, 3 and 4 IgE levels were measured. Statistical analyses were carried out using parametric and non-parametric tests. Results: anti-rPru p 1 and anti-rPru p 4 IgE levels were significantly higher in patients with mild OAS than in patients with severe OAS (p = 0.0001); in contrast, anti-rPru p 3 IgE levels were significantly higher in patients with severe OAS than in patients with mild OAS (p < 0.00005). Moreover, we found that any unitary increase in anti-rPru p 1 IgE values corresponded to a 2.48% reduction in the odds of having severe OAS (p = 0.048), whereas any unitary increase in anti-rPru p 3 IgE values corresponded to a 9.02% increase in the probability of having severe OAS (p = 0.001). Unexpectedly, we found that patients positive to rPru p 3 as well as rPru p 1 and 4 demonstrated a significant reduction of the odds of developing severe symptoms than those positive to rPru p 3 alone. Anti-rPru p 3 IgE levels were a significantly better indicator than anti-peach IgE values (p = 0.016) of patients with the highest risk for severe OAS. A cutoff of 2.69 kUA/l for anti-rPru p 3 IgE values better discriminated peach-allergic patients at a higher risk for symptoms. Conclusions: Italian patients with positive anti-rPru p 1, 4 and 3 IgE levels seemed less likely to experience the clinical effects of high anti-rPru p 3 IgE values.
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