Thank you for your inquiry.
I believe perhaps there may be some confusion regarding the case report that you cited (1). The reaction the patient experienced does not actually establish crossreactivity between pink peppercorns and other members of the family Anacardiaceae. No immunologic in vitro studies were performed to demonstrate actual crossreactivity. It is only implied because the pink peppercorns are in the same family as cashews. This group of plants has also been called the sumac family. It is of course reasonable to assume that a cross-reacting antigen may have been responsible since the patient was also allergic to cashews and pistachios, but unless immunologic studies are performed, one could not establish this definitively. But, as you note, it would not be unexpected for members of the same botanical family to crossreact even though this is not universally the case. This family includes a number of different plants besides cashew and peppercorn. Notably it contains mango, poison sumac, poison ivy, yellow mombin, the smoke tree, marula, and cuachalalate. Pistachio has been classified as part of this family as well, but some authorities place it in a family of its own (Pistaciaceae).
Of this family, probably the most extensive work regarding crossreactivity exists for cashew and pistachio. At least four distinct allergens have been noted in cashew including a vicilin-like protein, a profilin, an albumin, and a globulin. Very similar allergens are found in pistachio including an albumin, globulin, vicilin-like protein, and pistachio also contains a magnesium superoxide dismutase. There is also a possibility that a lipid transfer protein is an active antigen in pistachio.
Pistachio has a very close relationship, as noted, with the Anacardiaceae family. Numerous studies have of course demonstrated crossreactivity to cashew and pistachio. Additional foods cross-react with pistachio including mango and artemisia. Other cross-reactivities for pistachio based on case reports might be pectin and other foods containing the lipid transfer protein.
Similar but separate cross-reactive patterns have been seen for cashew. Evidence for cross-reactivity between cashew and other foods exists for hazelnut, walnut, and perhaps peanut. Some immunologic reactivity has also been noted for sesamum indicum and buckwheat. As with pistachio, pectin exhibits crossreactivity with cashew.
From the above, you can see that there is a very complex in vitro, immunologic crossreactivity pattern existing between cashew and pistachio and between these two foods and other allergens. Andin direct answer to your inquiry there is potential crossreactivity between both of these and any member of the Anacardiaceae family as evidenced by the single case of a patient exhibiting clinical reactions to peppercorn as well as cashew and pistachio.
None the less,from the above you also see it is difficult to draw any definitive clinical conclusions from these cross-reactive patterns except to say that there is probably an increased risk of clinical crossreactivity between all of the above mentioned foods with the strongest being for pistachio and cashew themselves.
Thank you again for your inquiry and we hope this response is helpful to you.
1. Kim J and Minikes N. A rare case of food-induced anaphylaxis to pink peppercorns. World Allergy Organization Journal 2012; 5:S152.
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Phil Lieberman, M.D.