Clinical features of four cases with cashew nut allergy and cross-reactivity between cashew nut and pistachio.

Hasegawa M, Inomata N, Yamazaki H, Morita A, Kirino M, Ikezawa Z
209-15 pages
Volume Jun;58(2)
BACKGROUND: Few cases of cashew nut (CN) allergy have been reported in Japan. We evaluated the clinical features of 4 cases with CN allergy and investigated the allergens involved. METHODS: In order to investigate the cross-reactivity between CN and pistachios; we performed ImmunoCAP inhibition tests using sera of 4 cases with positive histories of CN allergy and positive results of specific IgE measurement (ImmunoCAP) and skin prick tests. Furthermore; we analyzed the molecular weights of allergens of CN and pistachios by IgE-immunoblotting. RESULTS: Of the 4 cases (male : female = 1:3); there were 3 cases (patient #2-4) and 1 case (patient #1) of anaphylaxis and oral allergy syndrome; respectively. The initial symptom was an oropharyngeal symptom in 3 of the 4 cases; of which 2 cases developed anaphylaxis within 10 minutes after eating only a few pieces of CN. All 4 cases reacted positively to the skin prick test with CN; although 1 case of anaphylaxis tested negatively for CN by ImmunoCAP. Additionally; in 2 cases; IgE-binding to CN and pistachio were inhibited with both pistachios and CN; indicating cross-reactivity between CN and pistachios. IgE-immunoblotting of CN using sera from the 4 cases revealed 2 bands at molecular weights of approximately 33 kd and 42 kd; whereas that of pistachios showed a single band at 36 kd. However; IgE in all 4 sera did not bind to rAna o 2. CONCLUSIONS: In CN allergy; a small amount of CN could induce a severe anaphylactic reaction. Moreover; in cases of suspected CN allergy; reactions to not only CN but also pistachio; which could be cross-reactive to CN; should be examined.