Peanuts and Nuts as a Cause of Food Allergic Disease

Determining the nature of allergic components of food provides information that can be used to improve understanding of the cause and mechanism of food allergic disease. Isolating individual allergens helps to identify the substances responsible for the allergic response.
Immunological techniques are very sensitive at detecting small quantities and were used in this study to identify allergens in nuts.
Sera from a group of nut-allergic patients were used to characterise the allergens in five nuts frequently consumed in the United Kingdom: peanut (not a true nut), hazelnut, Brazil nut, almond and walnut.
Allergens in nuts were identified by the ability of immunoglobulins in the nut-allergic serum to bind to allergic proteins and protein subunits in nuts. These antibody-antigen complexes were identified by adding a radioactive label which was visulised on an autoradiograph. All five nuts were found to contain multiple allergens within a wide range of molecular weights. The nut-allergic serum pool contained both IgE and IgG antibodies to antigens in all the five nuts.
Individual serum was assayed with protein extracts from each of the nuts. Numerous allergens of varying importance were identified. A scoring system was developed to analyse the level of allergenicity of identified allergens. This was based on the strength of binding between antibody and allergen as seen on the autoradiograph.
The effect of heat was assessed and found not to alter the allergenicity of the nuts studied. Image analysis was developed to store and analyse data on nut allergens. The technique was found suitable to analyse autoradiographs, nitrocellulose membrane paper and sodium dodecyl sulphate polyacrylamide gels.