Identification of a 60 kd cross-reactive allergen in pollen and plant-derived food

Background: Cross-reactive IgE antibodies were found to be responsible for allergic reactions in patients allergic to pollen on ingestion of food (oral allergy syndrome). So far, the major birch pollen allergen Bet nu 1 and birch profilin (Bet nu 2) were identified as relevant cross-reactive allergens. Objective: In this study we attempted to identify additional cross-reactive plant allergens, which could be responsible for food intolerance in patients allergic to pollen. Methods: Monoclonal antibodies specific for the major mugwort pollen allergen, Art nu 1, representing a 60 kd glycoprotein, were used to defect cross-reactive allergens in other pollens and plant-derived food. The amino acid compositions of the cross-reactive structure were determined, and their resistance against trypsin treatment was investigated. In addition, IgE immunoblot inhibitions were done with the 60 kd mugwort pollen allergen. Results: Monoclonal antibodies specific for the major mugwort pollen allergen, Art nu 1, cross-reacted with proteins of comparable molecular weight in fruit and vegetables. Preadsorption of patients' sera with the 60 kd mugwort allergen led to a reduction of IgE binding to components of a similar molecular weight present in different pollen (birch, timothy grass), fruit (apple, peanuts), and vegetable (celery) extracts and reduced IgE binding to apple, kiwi, and celery as determined by RAST inhibitions. Conclusion: A cross-reactive plant panallergen, possibly identical to the major mugwort pollen allergen, Art nu 1, is described. The allergen represents a protein of approximately 60 kd present in various pollen and plant foods, which is distinct from Bet nu 1 and profilin and hence may represent a nor el cross-reactive allergen in the oral allergy syndrome.