D1.203 - Pine Nut Allergy in a Pediatric Patient with Multiple Sensitizations to Tree Nuts and Storage Proteins

Introduction:

Tree nut and seed allergies are among the leading causes of anaphylaxis in the pediatric population. However, allergic reactions to pine nuts (Pinus pinea) are less common and not as well characterized compared to other tree nuts.

Case Report:

We present the case of a 10-year-old boy with a history of moderate persistent asthma, allergic to mites, for which he is receiving specific immunotherapy. He also has documented allergies to shellfish (tropomyosins), kiwi, and multiple tree nuts (hazelnut, cashew, pistachio, almond, and walnut). At age 9, he experienced two anaphilactic reactions following the accidental ingestion of nuts. Recently, he ingested fewer than two pine nuts in a pie, which resulted in oral pruritus, a burning sensation in the mouth, dysphagia, and rhinitis.

Skin prick testing revealed a 9 mm wheal in response to pine nut extract, and his total IgE level was elevated (1166 UI/L). Immunological analysis using the ALEX platform demonstrated sensitization to the 2S albumin storage proteins from several tree nuts, including hazelnut, pistachio, cashew and walnut.

Methods and results: 

Protein extraction from pine nuts was performed, followed by SDS-PAGE and Western blot analysis. Western blot analysis revealed four major protein bands between 30-75 kDa, with specific IgE recognition in both reducing and non-reducing conditions. The allergenic profile did not match the known major pine nut allergen, Pin p 1 (2S albumin), which is commonly implicated in pine nut allergy. Instead, the patient’s serum showed reactivity towards storage proteins such as vicilins (7S globulins) and 11S globulins, suggesting an alternative sensitization pathway. (see Figure 1).

Discussion:

Although the patient exhibited cross-reactivity with 2S-albumins from other tree nuts, this case suggests that other storage proteins, such as vicilins and 11S-globulins, may play a primary role in his pine nut allergy. The low evolutionary homology between Pin p 1 and 2S-albumins from common tree nuts may explain the lack of significant cross-reactivity.

Conclusion:T

his case highlights the importance of identifying specific allergens in pine nut allergy and underscores the differences in cross-reactivity with other tree nuts. Further studies are needed to clarify the role of proteins like vicilins and 11S- globulins in pine nut allergic reactions.