A case of allergy to pomegranate and walnut: what is the role of lipid transfer protein Pru p 3?

Lipid transfer proteins (LTPs) are pan-allergens that are responsible for cross-reactivity between fruits, vegetables, and pollen. Pru p 3, the LTP present in the peach, is recognized as a marker of severity in food allergy. Pomegranate and walnut have been reported to be involved in allergic reactions due to the existence of LTPs. We report the case of a teenager admitted with rash and swollen lips after the ingestion of pomegranate, and reporting a similar reaction in the past after ingesting walnut. Skin tests showed positive results for commercial extracts of walnut and pomegranate pulp, and were negative for grass and peach. The total immunoglobulin E (IgE) was 87.2 IU/mL and specific IgE (sIgE) testing for walnut and hazelnut was positive. sIgE determination using the ISAC method (immuno-solid-phase allergen chip) was positive for hazelnut (Cor A 8), peach (Pru p 3) and walnut (Jug r3). There was no history of allergic reaction after the ingestion of peach. The present case questions the relevance of Pru p 3 in patients who are not allergic to peach, and whether this is the only cross-reactive marker with pomegranate.