The 2 Ara h 1 IgE, either individually or combined, at higher (100 IU/mL) or lower (10 IU/mL) concentration, could not mediate PCA reaction either challenged with 5 μg rAra h 1, or 10 μg CPE containing abundant nAra h 1, indicated that 2 different Ara h 1 IgE would not be able to mediate Ara h 1–induced allergic reactions. Here, IGHE is linked to allergic disease.