Allergenic Reactivity of Various Soybean Products as Determined by RAST Inhibition

One hundred thirteen patients with severe atopic dermatitis were evaluated for food hypersensitivity with double-blind placebo-controlled oral food challenges. Sixty-three (56%) children experienced 101 positive food challenges; skin symptoms developed in 85 (84%) challenges, gastrointestinal symptoms in 53 (52%), and respiratory symptoms in 32 (32%). Egg, peanut, and milk accounted for 72% of the hypersensitivity reactions induced. History and laboratory data were of marginal value in predicting which patients were likely to have food allergy. When patients were given appropriate restrictive diets based on oral food challenge results, approximately 40% of the 40 patients re-evaluated lost their hypersensitivity after 1 or 2 years, and most showed significant improvement in their clinical course compared with patients in whom no food allergy was documented. These studies demonstrate that food hypersensitivity plays a pathogenic role in some children with atopic dermatitis and that appropriate diagnosis and exclusionary diets can lead to significant improvement in their skin symptoms.

In order to extend previous investigations of adverse reactions to foods performed at this institution, 68 children, aged 5 mo to 15 yr, were studied. All subjects reported a history of adverse reaction to ingestion of one or more of the 14 foods under study. Sixteen of 43 subjects, 3 yr of age or older, had 22 adverse reactions during 94 food challenges with one or more of the 14 foods. All reactions confirmed were to peanut or other nuts, milk, egg, and soy. Skin testing with 1:20 weight/volume concentrations of food extracts applied by the puncture technique produced a net wheal reaction 3 mm or greater in all subjects 3 yr of age or older in whom double-blind food challenges confirmed the history of adverse reaction. Thirteen of 25 children less than 3 yr of age manifested adverse reactions during 49 food challenges. Skin testing by puncture technique produced a net wheal 3 mm or greater in 9 children less than 3 yr of age in whom food challenge elicited a clinical response within 2 hr. One of 4 subjects less than 3 yr of age in whom the adverse reaction occurred more than 4 hr after food challenge exhibited a wheal to puncture skin test of 3 mm or greater. These studies suggest that at present double-blind food challenge is an indispensible tool for the unequivocal evaluation of adverse reactions to foods.