Anaphylaxis to pine nut: cross-reactivity to Artemisia vulgaris?

The use of pine nuts, the seeds of Pinus pinea, is on the increasing in the modern Mediterranean diet. Little more than 20 cases of allergy to this tree nut have been published, and cross-reactivity with pine pollen, peanut and almond has already been reported. We describe the case of a young boy with several episodes of anaphylaxis after pine nut ingestion. Specific IgE to pine nut and Artemisia vulgaris was demonstrated by skin prick tests and in vitro determination of specific IgE, although no IgE to pine pollen or other nuts was detected. Immunoblotting of Artemisia vulgaris and pine nut revealed two matching diffuse bands, just below 14 kDa and 30 kDa. The ImmunoCAP inhibition assays showed complete inhibition of pine nut specific IgE after serum incubation with Artemisia vulgaris extract. As far as we know, this is the first reported case of documented cross-reactivity between pine nut and Artemisia vulgaris.