STABILITY OF CEREAL ALLERGENS

Background Ingested cereals and inhaled cereal dusts can cause IgE-med iated allergy. Testing for these allergies yields variable, often unde pendable results, which could be due to the use of unsuitable or degra ded testing materials. Objective We studied the effect of storage medi a, time and temperature on the stability of protein allergens extracte d from wheat, rye, barley and oats flour. We also examined the effect of heat processing similar to that used when preparing foods on the st ability of allergenic proteins present in wheat flour. Methods After s torage experiments proteins in allergen extracts were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and then vis ualized using immunoblotting or staining with Coomassie brilliant blue . After heat processing wheat flour proteins were extracted and their IgE-binding capacity was estimated. Results Extracted proteins from wh eat, rye and barley flour appeared stable for at least 21 months when stored at 4 degrees C in an aqueous solution containing 50% glycerol a nd 0.45% sodium chloride. In a medium with 0.4% phenol and 0.9% sodium chloride degradation of many proteins became apparent already after 1 month of storage. Oats extracts lost their IgE-binding capacity more rapidly and the maximal storage time appeared to be 10 months at 4 deg rees C in a solution containing 50% glycerol and 0.45% sodium chloride . The IgE-binding capacity of the allergenic proteins decreased as hea t-processing temperature and heating time increased. No processing con ditions entirely abolished IgE-binding. Conclusion Cereal allergen pre parations can be stored either in lyophilized form or at 4 degrees C i n 50% glycerol. Unheated materials should be used also when testing fo r food allergy, as heating reduces allergenicity and thus sensitivity at testing.