Proteins Responsible for Fruit allergies in the Northwest of Spain.

Plant allergies are a frequent cause of visits to the allergologist. In the Alergologica 2005 study carried out in Spain, fruits were the main cause of food allergies [1]. Plant allergies in a specific population are related to consumption habits and to the pollen pattern of the region under study. The objective of this retrospective study was to determine the proteins responsible for fruit allergies in Asturias, a region situated on the Cantabrian Sea with an Atlantic climate and a pollen pattern different to that of the rest of Spain. We recruited patients diagnosed with fruit allergy from a database of patients seen in an outpatient clinic between 2010 and 2013. To be included in the study, all patients had to present a clinical picture characteristic of IgE-mediated allergy to fruits, with a positive prick-prick test or skin prick test result (ALKAbelló) with the culprit fruit. Sensitization to panallergens such as profilin, lipid transfer protein (LTP), and birch extract, as well as to Lolium extract was determined by skin prick test (ALK-Abelló), ImmunoCAP (Phadia) (rPhl p 12, rPru p 3, and nBet v 1), and ISAC 112 (Thermo Fisher Scientific). In vitro techniques were only used when the panallergen was not identified using the skin tests. The ImmunoCAP test was ordered for 10 patients and the ISAC test for 15. The study sample comprised 56 patients (29 men) with a median age of 29 years (IQR, 20-40). Symptoms triggered by Rosaceae fruits were detected in 22 patients (39%), kiwi in 16 patients (29%), peach only in 12 patients (21%), melon in 6 patients (11%), and banana in 4 patients (7%). Less frequent reactions were observed for fig, apple only, and orange (2 cases each, 4%) and avocado, strawberry, cherry, and passion fruit (1 case each, 2%). As for clinical manifestations, 63% of patients presented oral allergy syndrome (OAS), 16% urticaria/angioedema, 12% anaphylaxis, 5% contact urticaria, and 4% digestive symptoms. The proteins responsible for the reactions were LTPs (17 cases [30%]), pathogenesis-related (PR) protein 10 (17 cases [30%]), profilins (6 cases [11%]), Act d 1 (5 cases [9%]), unknown proteins (5 cases [9%]), PR-10 and profilins (4 cases [7%]), thaumatins (1 case [2%]), and chitinasaes (1 cases [2%]). The relationship between the type of fruit and the sensitization identified is shown in the Table. Only one-third of patients who were allergic to PR-10 had symptoms caused by allergy to Betulaceae pollen. However, 90% of those who were allergic to profilins had symptoms caused by allergy to grasses. Most cases of fruit allergy were caused by members of the Rosaceae family. PR-10 were the triggering proteins in 70% of cases. In a recent review of allergy to Rosaceae in Europe, PR-10 was shown to be of minor importance in Spain, as levels of sensitization were very low (0%-13%) [2]. Our findings contrast sharply with this result and are more consistent with findings from central Europe and Scandinavia, although in these regions, allergy to Rosaceae is significantly associated with allergy to pollen from Betulaceae, while in our region this was the case with only one-third of patients. Sensitization to profilin in patients who are allergic to Rosaceae in Spain has been reported to range from 56% to 80% [2]. In our study, levels were markedly lower (23%). Kiwi was the second most common cause of allergy, representing almost one-third of all cases. Act d 1 was the most frequently involved protein (one-third of cases). Curiously, this figure is similar to that found for Iceland in a recent European study on allergy to kiwi [3]. The proteins PR-10, LTP, and profilin all accounted for a similar percentage of cases. These Table. Culprit Allergens From the Fruits Involved in the Reactions