Tree nuts allergy

Abstract

Allergy to tree nuts is on the rise in Japan: tree nuts were the third most common causative allergen in a national survey of immediate-type reactions in 2020 and the most reported causative allergen in a comprehensive survey of pediatric anaphylaxis conducted in Aichi Prefecture. Walnuts, cashews, almonds, and macadamia nuts, in that order, are the most frequently ingested tree nuts. The usefulness of component-specific IgE antibody titers in diagnosing tree nut allergy has been widely reported. Measurement of specific IgE titers of Jug r 1 and Ana o 3 allergens, which are 2S albumins in walnuts and cashew nuts, respectively, are covered by universal health insurance in Japan. Due to reported cutoff points of 0.98 U_A/mL for Jug r 1 and 2.20 U_A/mL for Ana o 3 for 95% positive predictive value, patients with values higher than these should be regarded as allergic to the specific nuts. Specific IgE antibody titers against 11S globulin in almonds and 7S globulin in macadamia nuts have also been reported to have diagnostic utility. Oral immunotherapy has been reported to be effective for tree nut allergies.