Anacardiaceae

Anacardium occidentale

Allergy to cashew nuts is not uncommon. In a retrospective case note study of 117 children who presented with anaphylaxis the median age of presentation was 2.4 years; there was one death [ ]. The most common triggers were foods (85%), including peanuts (18%) and cashew nuts (13%). The median time from exposure to anaphylaxis for all identifiable agents was 10 minutes. Cashew nut allergy can be associated with allergy to other foods, including pectin [ ].

Of 65 patients who had skin tests with an extract of pollen from Anacardium occidentale (cashew), 26 (40%) had positive reactions [ ]. Of 22 of these 26 patients, 20 had a positive bronchial provocation test and most had grade III or IV reactions. None of 10 control subjects had positive responses to either intradermal tests or bronchial provocation. Serum IgE concentrations were high in patients with positive skin test responses and correlated with cutaneous sensitivity; IgE concentrations in the controls were not raised.

Of 42 children with cashew allergy and onset before the age of 3 years, 24 had skin symptoms, 25% had respiratory signs and 17% had digestive signs; 18 had associated food allergies (pistachio, 7; egg, 5; mustard, 3; shrimp, 2; cow's milk, 1) [ ]. Lack of peanut allergy, as observed in these children has also been reported elsewhere [ ].

The allergens associated with allergy to cashews food have been studied in 15 subjects who had had life- threateningreactions to cashews and eight who tolerated cashews but had had life-threatening reactions to other tree nuts [ ]. Each of the serum samples from the cashew-allergic subjects showed IgE binding to a cashew protein extract. The dominant IgE-binding antigens in the reduced preparations included peptides in the 31–35 kDa range, consistent with the large subunits of the major storage 13S globulin (legumin-like protein); low-molecular-weight polypeptides of the 2S albumin family, similar to the major walnut allergen Jug r 1, also bound IgE. The sera from the eight controls showed only minimal or no IgE binding to cashew. In another study the 2S albumin responsible was designated Ana o 3, to which 21 of 26 sera from patients with cashew allergy were reactive; it was similar to an allergen found in walnuts [ ].