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Identification of Japanese Apricot Peamaclein As a New Allergen Related to Food-Dependent Exercise-Induced Anaphylaxis Due to Japanese Apricot: Cross-Reactivity to Pru p 7
Monday, March 7, 2016
South Exhibit Hall H (Convention Center)
Naoko Inomata, Mami Miyakawa, Asa Hotta, Michiko Aihara
Rationale: In previous research, we identified peach peamaclein (Pru p 7) as an allergen related to systemic reactions in peach allergy. We hypothesized that Japanese apricot (JA) peamaclein may be a new allergen related to food-dependent exercise-induced anaphylaxis (FDEIA) due to JA.

Methods: Seven patients (M:F=2:5, mean age 28.6 yrs) diagnosed with JA allergy based on relevant clinical history, positive skin test and/or challenge test were enrolled. To evaluate the allergenicity of the purified JA peamaclein, we performed ELISA and IgE-immunoblotting using the patients’ sera with JA peamaclein. ELISA with nPru p 7 was conducted. Using ImmunoCAP, we measured specific IgE levels against peach, rPru p 1, rPru p 3, and rPru p 4.  We also performed basophil activating tests (BATs) for JA peamaclein. To investigate the cross-reactivity between JA peamaclein and Pru p 7, we performed ELISA inhibition tests.

Results: Exercise after intake of JA was followed by the onset of allergic reactions in six patients’ self-reports and one patient’s challenge test. The ELISA and IgE-immunoblotting using JA peamaclein showed positive reactions in six (85.7%) and seven (100%) patients, respectively. The positivity for specific IgE against peach, rPru p 1, rPru p 3, rPru p 4 and nPru p 7 was 57.1%, 0%, 0%, 0% and 85.7%. JA peamaclein induced basophil CD203c expression in all four patients who underwent BATs. In all four patients who underwent ELISA inhibition tests, IgE binding to one peamaclein inhibited binding to the other.

Conclusions: Peamaclein is a causative allergen of FDEIA due to JA, and is a cross-reactive allergen between JA and peach.