Evaluation of IgE antibodies to recombinant peanut allergens in patients with reported reactions to peanut.

BACKGROUND Peanut may cause severe reactions in allergic individuals. The objective was to evaluate IgE antibodies to various recombinant (r) peanut and birch pollen allergens in relation to IgE levels to whole peanut extract and severe allergic reactions to peanut. METHODS Seventy-four Swedish peanut-allergic patients (age: 14-61 years) reported previous peanut exposure and associated symptoms using a questionnaire. Their IgE reactivity to peanut, birch pollen and individual allergen components was analyzed using ImmunoCAP. RESULTS Of the 48 subjects sensitized to Ara h 1, 2 or 3, 60% had peanut-specific IgE levels >15 kU(A)/l, while 100% of the subjects without detectable IgE to these allergens had low peanut-specific IgE levels (<10 kU(A)/l). The levels of IgE to rAra h 8, rBet v 1 and birch pollen were highly correlated (r(S) = 0.94, p < 0.0001). Fifty-eight patients reported adverse reactions after accidental or deliberate peanut exposure (oral, inhalation or skin) of whom 41 had IgE to rAra h 1, 2 or 3. Symptoms of respiratory distress were associated with sensitization to Ara h 1, 2 or 3 (56 vs. 18%, p < 0.01). Two cases of anaphylaxis were reported among the individuals sensitized to Ara h 1-3. IgE to rAra h 8, rAra h 9, profilin or cross-reactive carbohydrate determinants were not associated with severe symptoms. CONCLUSIONS The results indicate that IgE reactivity to Ara h 1, 2 and 3 is associated with severe reactions after exposure to peanut in Swedish patients.