Characterization of allergens in kiwi fruit and detection of cross‐reactivities with allergens of birch pollen and related fruit allergens

The sera of 29 patients who suffered from pollen‐related food hypersensitivities and complained of allergic reactions to kiwi fruit and other tropical fruits were tested for specific IgE antibodies against kiwi fruit, apple, carrot, celery and birch pollen using an enzyme allergosorbent test (EAST). In 20 sera, specific IgE antibodies were detected against all five extracts. Sodium dodecyl sulphate polyacrylamide gel electrophoresis/ immunoblot of kiwi fruit extract revealed two major allergens with molecular weights of approximately 43 and 67 kDa. In EAST inhibition assays, cross‐reactivities between kiwi fruit, apple, birch pollen and, to a lesser degree, carrot and celery were demonstrated. The cross‐reactivities seen between kiwi fruit, birch pollen and apple were not caused by the major allergen of birch pollen (Bet v 1). Allergens with molecular weights of approximately 68 kDa in birch pollen and 67 kDa in apple cross‐reacted with the allergens of kiwi fruit, as demonstrated by immunoblotinhibition. Profilins, which are known plant pan‐allergens, do not seem to be relevant allergens in kiwi fruit.