1. Severe allergic reaction to pine nut
Barbarroja-Escudero, Jose1; Antolin-Amerigo, Dario1; Sanchez-Gonzalez, Maria-Jose1; Ledesma, Amalia2; Carpizo, Jose2; Alvarez-Mon Soto, Melchor1; Rodriguez-Rodriguez, Mercedes1
1 Hospital Universitario Principe de Asturias, Allergy Division. Immune System Diseases & Oncology Service, Alcala de Henares. Madrid, Spain
2 ALK-Abello, Biochemical Laboratory, Madrid, Spain
Background
Pine nuts are the edible seeds derived from several varieties of Pine trees (i.e. Pinus pinea). They are used as ingredient in salads, pastries, sauces and diverse culinary recipes or even as roasted nuts. Food allergy to pine nuts has been barely reported in the literature.
Method
We present a 18-year-old girl who had, when she was 4 and 14 years old, two anaphylactic reactions after eating a single pine nut and a sausage outside the home environment, respectively. Up-to-date, she tolerates all foods including peanut, almond, sunflower seed and the rest of tree nuts. She had never suffered from rhinoconjunctival nor asthma symptoms. We carried out in vivo (skin prick test, prick-by-prick) and in vitro tests (total and specific IgE determinations [CAP-FEIA], immunoblotting SDS-PAGE, and Blotting-inhibition). The latest one was performed to rule out evidence for cross-reactivity of pine nut with a series of pollens (Olea europea, Pinus pinea, Artemisia vulgaris, and Lolium perenne) whose cross-reactivity has been previously proved. 
Lane 1
Lane 2
Result
Skin prick testing against commercial common aeroallergens, profilin and LTP were performed with positive result (wheal 3 mm) exclusively against Olea europaea. Skin prick-by-prick testing to raw and cooked pine nuts were all positive, unlike the rest of the nuts tested. IgE total was 73 UI/ml, specific IgE to pine nut of kU/L and specific IgE to nOle e 1 of 0.73 kU/L. The rest of specific IgE to nuts was negative. SDS-PAGE IgE-immunoblotting assays were performed revealing IgE-reactivity at 30, 50 and 80 kDa. Additional weaker bands were observed at 14, 40 and 100 KDa. We did not find cross-reactivity with Olea europea, Pinus pinea, Artemisia vulgaris, and Lolium perenne pollens. 
Pine nut IgE-immunoblotting. Lane 1: incubated with the patient's serum. Lane 2: negative control in the absence of serum. M, molecular weight markers (M.W. are indicated in kDa).
Conclusion
We present a rather unusual case of anaphylaxis due to pine nuts ingestion in a monosensitized woman. Monosensitization of this seed has not evolved into subsequent sensitization to additional nuts, seed or pollens. Pine nut should be kept in mind as a potentially hidden allergen. Further investigation must be carried out in order to enlighten the cross-reactivity of this seed and to clarify its clinical relevance owing to severity of reactions which pine nut may cause.
References
Ibáñez MD, Lombardero M, San Ireneo MM, Muñoz MC. Anaphylaxis induced by pine nuts in two young girls. Pediatr Allergy Immunol 2003:14:317–9.
Añó MA, Maselli JP, Sanz ML, Fernández-Benítez M. Allergy to pine nut. Allergol Immunopathol 2002;30(2):104-8.
Rodrigues-Alvesa R, Pregala A, M.C. Pereira-Santos MC, Branco-Ferreira M, Lundberg M, Öman H, Pereira-Barbosa M. Anaphylaxis to pine nut: cross-reactivity to Artemisia vulgaris?. Allergol Immunopathol 2008;36(2):113-6.
Armentia A, Quintero A, Fernández-García A, Salvador J, Martín-Santos JM. Allergy to pine pollen and pinon nuts: a review of three cases. Ann Allergy 1988;64:49-53.
Senna G, Roncarolo D, Dama A, Mistrello G. Anaphylaxis to pine nuts and immunological cross-reactivity with pine pollen proteins. J Invest Allergol Clin Immunol 2000;10:44-6.
Cornflod CA, Fountain DW, Burr RG. IgE-binding proteins from pine (Pinus radiata) pollen: evidence for cross-reactivity with ryegrass (Lolium perenne). Int Arch Allergy App Immunol 1990:93:41-6.