Theme 3: Allergen structure and the Food Matrix
Leader: Clare Mills
Overall aim
Theme 3 aims to refine tests for food specific IgE using well-defined allergenic molecules (allergens) and to improve the predictive value of the tests in particular with respect to symptom severity and their ability to distinguish clinically relevant cross-reactions since clinically irrelevant positive in vitro test result may arise from low affinity cross-reacting IgE (e.g. between pollens and foods, between peanut and other legumes). Detection of specific IgE directed against stable allergens can be an indication for severe reactions against allergenic foods. Similarly, the specificity of in vitro serological diagnosis of food allergy could be improved by novel functional tests that measure the biological activity of allergens by recognising clinically irrelevant sensitisation caused by low affinity IgE antibodies.
This will be realised by using a combination of highly purified and structurally characterised food allergens and to develop novel diagnostic methods which will enable component resolved diagnosis and also work towards an in vitro method of biological effectiveness of IgE similar to a “DBPCFC-in-a-tube”.
1. Allergen library (Work Leader: Karin Hoffman-Sommergruber)
A collection of natural and recombinant allergens will be assembled. Allergens will be characterised with regards structure (primary to quaternary) and post-translational modification (including glycosylation) and the presence of different isoforms.
2. Novel Diagnostics (Work Leader: Stefan Vieths)
A fast high-through-put in vitro serological analysis which yields results linked to clinical symptoms is needed as an alternative to Double Blind Placebo Controlled Food Challenge (DBPCFC). Such tests would benefit routine clinical diagnosis of food allergy (and hence benefit allergic consumers) and would facilitate future epidemiological studies. Current in vitro alternatives sufferfrom low specificity (false-positive results) and low sensitivity (false-negative results). In order to address these issues the project will refine tests for food specific IgE using well-defined allergens and to improve the predictive value of the tests by
- Validating component-resolved diagnostic methods utilizing the allergen library and clinical cohorts from Theme 1;
- Developing novel protein chip diagnostics to facilitate component-resolved diagnosis utilizing very small samples of allergens from the allergen library and sera;
- Developing novel cell-based tests that measure the biological activity of allergens.
3. The food matrix and allergenic potential (Work Leader: Harry Wichers)
Assessing the allergenic potential of foods is undertaken, with in the regulatory framework of the EU Directive regarding Novel Foods and Processes and requires an integrative multifaceted approach and involves several different factors, including the characteristics of the food in question. Theme 3 will investigate how the following may impact on the allergenicity of foods as we eat them:
- Structural features and physicochemical properties of proteins;
- Interactions within complex food matrices (both natural and fabricated structures) and the changes induced by processing (so-called neoallergens) ;
- Interactions between allergen structure, the matrix AND the digestive and metabolic processes, including hitherto uncharacterised adjuvant effects of the matrix structure.