Immunoglobulin E-binding Proteins of Cooked Walnuts in Korean Children

Abstract

PurposeThe immunological characteristics of young Korean children with walnut (WN) allergy and the influence of different cooking methods on WN proteins have not been evaluated to date. This study aimed to evaluate the major WN allergens identified among Korean children, together with changes in WN antigenicity caused by common cooking methods.MethodsWe enrolled children under the age of 13 years with WN serum-specific immunoglobulin (Ig) E concentrations. The protein fractions of dry-fried and boiled WN extracts were compared with those of raw WNs using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), 2-dimentional gel electrophoresis (2DE) and a proteomic analysis using electrospray ionization (liquid chromatography-mass spectrometry [LC-MS]). An immunoblotting analysis was conducted to examine IgE reactivity toward raw WNs using serum samples from 6 children with a clinical WN allergy. To determine the processed WN proteins with IgE-binding capacity, a 2D-immunoblotting analysis was performed using the pooled sera of 20 WN-sensitized children.ResultsProtein bands from raw WNs were identified at 9, 16, 28, 52, 58, and 64 kDa via SDS-PAGE. The 9- and 16-kDa protein bands were enhanced by boiling, whereas the 52- and 64-kDa bands were considerably diminished. On LC-MS analysis, of the 66 IgE-binding proteins present in raw WNs, 57 were found in dry-fried WNs, but only 4 in boiled WNs. The sera of 5 out of 6 participants reacted with the 52-kDa protein bands and those of 4 out of 6 participants reacted with the 16- and 28-kDa protein bands, respectively. Meanwhile, a 2D-immunoblotting result confirmed the presence of different binding patterns among children who consumed cooked WNs.ConclusionsThe protein profile of boiled WNs is substantially different from that of raw WNs. However, 4 proteins including prolamins remained stable after dry-frying or boiling. Further studies are needed to evaluate the clinical relevance of these findings.

Is There Any Necessity to Prescribe Consumption of Walnuts Cooked by Different Processing Techniques to Patients With Walnut Allergy?

“…The present study on this issue focused on identifying the usual methods of cooking walnuts in order to investigate changes in walnut allergen activity caused by cooking and evaluated the allergenic changes in walnut proteins within raw, dry-fried and boiled walnuts. 17 In addition, the effects of different cooking methods showed that of the 66 proteins, 57 were found in untreated walnuts with dry-fried walnuts and only 4 were seen in boiled walnuts. Interestingly, the remaining allergenic components of cooked walnuts cause serious reactions when consumed by children.…”

“…A few studies have looked for combinations of processing methods to alter the allergenicity of foods. 17 18 However, there are different views with regard to walnut allergy. Some treatments, such as dry-roasting can reduce IgE-binding capacity in vitro .…”