Detecting Anti-Cashew IgE

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Description:  Approximately 0.5% of the US population is believed to be allergic to tree nuts. Additionally, the data from a voluntary registry of peanut and tree nut allergic US patients shows 20% of those reporting allergy to tree nuts list sensitivity to cashews, the highest percentage for any tree nut. The proposed invention discloses major allergenic proteins in cashew nut, which are legumin-like proteins and 2S albumins. Also disclosed is a polypeptide allergen in the 7S superfamily, which includes vicilin-like and sucrose binding proteins. Several linear epitopes of the cashew nut are identified and characterized. The invention further discloses the sequence of cDNA encoding the allergenic polypeptide, the allergen being designated Ana o 1, and also describes the characterization of the expressed recombinant polypeptide and associated methods employing the polypeptide. A diagnostic test for detecting anti-cashew IgE in a patient to thereby indicate an allergy to cashews comprises of: reacting patient's serum with a composition comprising at least one of the above mentioned purified polypeptide; separating the polypeptide from unreacted patient serum; reacting the polypeptide with a labeled human IgE-reactive agent after separating from unreacted patient serum; separating the polypeptide from unreacted labeled human IgE-reactive agent; and directly or indirectly detecting the labeled human IgE-reactive agent bound to the polypeptide after separating from unreacted agent to thereby indicate presence in the patient's serum of anti-cashew IgE.