Anaphylaxis to Sunflower Seed With Tolerance to Other Nuts: The Role of Lipophilic Allergens.

Abstract

Sunflower (Helianthus annuus) belongs to the genus of the Asteraceae plant family (Compositae). Sunflower seeds are consumed throughout the world, and patients who are allergic to other nuts usually tolerate them. Sunflower seed allergy is rare. Very few cases of anaphylaxis after ingestion have been described [1-5], with most involving an occupational origin in exposed workers [2,4]. Several allergenic proteins have been identified in sunflower seeds [1,3,4,6] and are documented by the World Health Organization/International Union of Immunological Studies Allergen Nomenclature Sub-Committee [www. allergen.org], as follows: Hel a 1 (34 kDa, a major inhaled allergen with no specific protein family described to date); Hel a 2 (a 14.7-kDa profilin); Hel a 3 (a 9-kDa lipid transfer protein [LTP], food allergen); and Hel a 6 (a 42-kDa pectate lyase, inhaled allergen). Others, such as Hel a 2S albumin (16 kDa), a 12-kDa storage protein that appears to be the mature form of Hel a 2S albumin, and a 13-kDa LTP, have also been described as potential allergens in other publications [1,5,6]. We present a case of anaphylaxis after ingestion of sunflower seeds in a patient sensitized to other nuts, all of which he tolerated. A 35-year-old man with a personal history of atopy (egg allergy in childhood that resolved and seasonal rhinoconjunctivitis) experienced lingual and palmoplantar pruritus, generalized hives, facial angioedema, conjunctival injection, dyspnea, and intense cough 5 minutes after eating a handful of roasted sunflower seeds (previously well tolerated). He went to the emergency department (blood pressure 128/65 mmHg and baseline SatO2 of 95%) and was treated with intravenous antihistamines and corticosteroids. His condition gradually improved within the following hour. No cofactors were identified. A series of complementary tests were carried out. Commercial skin prick tests (ALK-Abelló) were performed with peanut, walnut, pistachio, almond, hazelnut, chestnut, sunflower seed, peach LTP, profilin, mustard, and mugwort. The results were positive only for sunflower seed (12 mm). Prick-prick test with hazelnut, walnut, peanut, almond, and pistachio. The results were positive only for hazelnut (9 mm) and walnut (7 mm). Sunflower seed was not tested owing to the 12-mm skin prick test result and a moderate initial reaction. ImmunoCAP (ThermoFisher) revealed the following: total Immunoglobulin E (IgE), 124 IU/mL; specific IgE against sunflower seed, 3.18 kUA/L; almond, 0.11 kUA/L; cashew, 0.06 kUA/L; hazelnut, 0.27 kUA/L; peanut, 0.14 kUA/L; walnut, 0.27 kUA/L; pistachio, 0.18 kUA/L; and rPru p 3 (peach LTP), 0.01 kUA/L. ImmunoCAP ISAC 112 (ThermoFisher) revealed the following: moderate-to-high levels of cypress allergen (Cup a 1), 10.30 ISU; group 1 timothy grass pollen allergens, 2.76 ISU; and Alternaria (Alt a 1), 4.90 ISU. The results were negative for all nut proteins included. Open oral challenges with roasted hazelnuts and walnut were negative. The patient tolerated peanuts, almonds, pistachios, and cashews. Proteins from hydrosoluble and liposoluble fractions of peanut, hazelnut, walnut, and sunflower seed extracts were obtained using SDS-PAGE following the method described by Barbarroja-Escudero et al [7]. After the homogenization and extract centrifugation processes, the liposoluble fraction was separated from the hydrosoluble fraction, and each was treated independently to obtain the aqueous and oil-body extracts [7]. SDS-PAGE of the extracts revealed proteins ranging from 10