DETECTION OF ALLERGY TO NUTS BY RADIOALLERGOSORBENT TEST

[摘要] The diagnosis of food allergy is often difficult to make by conventional means. Histories are frequently ambiguous, and skin testing is of dubious reliability because of the number of false-positive and false-negative reactions. The radioallergosorbent test (RAST) was evaluated for the in vitro measurement of specific IgE [immunoglobulin E] antibodies to nuts, including Brazil nub, almond, walnut, pecan, cashew and peanut. Sera were obtained from 18 patients with a history of nut allergy, and IgE level and specific IgE antibodies were measured. Of the 18 patients, 13 had significantly elevated IgE antibody (greater than twic control) to 1 or more of the allergens. Prausnitz-Kestner tests on selected serums in general corroborated the results of the in vitro studies. Five patients had RAST elevations to 2 or more nuts. As a group, RAST-positive patients had elevated mean serum IgE levels and more severe clinical symptoms (P < 0.01). The specificity and cross-reactivity of IgE antibodies to different nut antigens was investigated by RAST inhibition with sera from 5 patients having high levels of IgE antibody. In 4 patients, no cross-reactivity between Brazil nut and peanut was found. Several nut extracts inhibited the reaction of pecan allergen with IgE antibodies. Specific IgE antibodies can be measured by RAST in patients with nut allergy, and the cross-reactivity of nut antigens can be investigated. RAST would appear to be most useful in confirming the diagnosis of nut hypersensitivity in children or in highly allergic patients in whom skin testing poses a risk of anaphylaxis.