Pollen-food syndrome involving allergy to tiger nut.

Tiger nut (Cyperus esculentus) is a small tuber native to warm and subtropical regions in the Northern Hemisphere. It is known to have been cultivated in ancient Egypt. Nowadays, it is mainly cultivated, at least for commercial purposes, in the Valencian Community of Spain. High in À ber, proteins, and natural sugars, it is consumed dried or as a vegetable milk extracted directly from the tuber. Although tiger nut has been consumed for a long time, very few cases of allergy after its ingestion have been reported [1-3]. We report on 3 patients aged 47, 23, and 15 years (P1, P2, and P3, respectively) with a history of oral pruritus and dysphagia (P1, P2, and P3) and chest tightness (P1) within minutes of eating tiger nut. All the patients also presented adverse reactions to other fruits, namely peach peel (P1), banana, melon, and coconut (P2), and fruits belonging to the rosacea family (P3). Concomitant atopic conditions were seasonal rhinoconjunctivitis (P1, P2, and P3) and seasonal asthma (P2 and P3). Skin prick tests to commercial extracts from common inhalants and to natural proÀ lin (Pho d 2) and peach extract enriched with Pru p 3 (as a lipid transfer protein [LTP] marker) as 2 of the main panallergens involved in pollen-food syndrome (PFS) were performed. The results are shown in the Table. Prick-by-prick tests with tiger nut showed a positive result (wheal •3 mm) in the 3 patients. Tiger nut protein extract (TN) was prepared by homogenization in phosphate-buffered saline, dialyzation, and lyophilization. SpeciÀ c immunoglobulin E (sIgE) determinations against TN disclosed positive values (>0.35 kU A /L) for all 3 patients. sIgE against Pru p 3 and against proÀ lin from different pollen were also carried out (see the Table). Serum speciÀ c IgE levels were measured in all cases with the enzyme allergosorbent technique (SpeciÀ c IgE EIA kit, HYTEC HYCOR Biomedical Ltd.). Tiger nut extract was analyzed by sodium dodecyl-polyacrylamide gel electrophoresis (SDS-PAGE) [4], which showed protein bands ranging between 12 and 97 kDa. SDS-PAGE immunoblotting revealed IgE reactivity with proteins ranging from 66 to 28 kDa and a 16-kDa protein with the 3 sera; a 14-kDa protein was also detected with serum from P2 and P3. SDS-PAGE immunoblotting inhibition assays using TN in the solid phase and the main relevant pollen in our environment as inhibitor phases were carried out. They showed complete inhibition of IgE binding …