Molecular characterization of walnut allergy in paediatric patients: identification of oleosins as a potentially new lipophilic allergens.

In the last decades, food allergy has been revealed as an important public health problem affecting the worldwide population, and in the most delicate age group such as children, can cause severe symptoms. Specifically, walnut allergens often induce anaphylactic reaction in paediatric and adult allergic patients, therefore timely and certain diagnosis is essential to avoid dangerous complications and restore patients’ quality of life. Currently, the diagnostic tests for food allergy are mainly based on hydrophilic allergens, underestimating the relevance of the lipophilic component. In this work, raw and boiled walnuts proteins were differentially extracted, characterized by LDS-PAGE and the patient IgE immunoreaction vs walnut hydrophilic and hydrophobic protein extract were evaluated. By using mass spectrometry, we identified all the already known walnut allergens and four oleosins were found out in the walnuts lipophilic fraction. Our investigations suggested that boiling may slightly modify walnuts allergenicity for both hydrophilic and hydrophobic protein extracts, although this finding have to be confirmed on a larger number of patients.