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White lupin is considered to be a rich source of protein with a notable content of lysine and is being increasingly used in bakery, confectionery, snacks and pastry products due to its multifunctional properties, in addition to its potential hypocholesterolemic and hypoglycemic properties. However, lupin seed flour has been reported as a causative agent of allergic reactions, especially in patients with allergy to peanut since the risk of immunological cross-reactivity between lupin and peanut is higher than with other legumes. Previously, we had identified two proteins as major lupin allergens (34.5 and 20 kDa) as determined by IgE immunoblotting using sera of 23 patients with lupin-specific IgE. The aim of this study was to purify and characterize the two major lupin allergens. The results using in vitro IgE-binding studies and MS analysis have shown that the 34.5 kDa allergen (Lup-1) is a conglutin β (vicilin-like protein) while the 20 kDa allergen (Lup-2) corresponds to the conglutin α fraction (legumin-like protein). The high level of amino acid sequence homology of Lup-1 and Lup-2 with the major allergens of some legumes explains the IgE cross-reactivity and clinical cross-reactivity of lupin and other legumes.

Enzymatic hydrolysis and further processing are commonly used to produce hypoallergenic dietary products derived from different protein sources, such as cow's milk. Lentils and chickpeas seem to be an important cause of IgE-mediated hypersensitivity in the Mediterranean area and India. Some studies have investigated the effects of enzymatic treatments on the in vitro immunological reactivity of members of the Leguminosae family, such as soybean, chickpea, lentil, and lupine. Nevertheless, there are only a few studies carried out to evaluate the effect on IgE reactivity of these food-hydrolysis products with sera from patients with well-documented allergy to these foods. In this study, lentil protein extract was hydrolyzed by sequential action of an endoprotease (Alcalase) and an exoprotease (Flavourzyme). Immunoreactivity to raw and hydrolyzed lentil extract was evaluated by means of IgE immunoblotting and ELISA using sera from five patients with clinical allergy to lentil. The results indicated that sequential hydrolysis of lentil results in an important proteolytic destruction of IgE-binding epitopes shown by in vitro experiments. However, some allergenic proteins were still detected by sera from four out of five patients in the last step of sequential hydrolyzation.

Background: A considerable number of pollen-allergic patients develops allergy to plant foods, which has been attributed to cross-reactivity between food and pollen allergens. The aim of this study was to analyze the differences among pollen-allergic patients with and without plant food allergy., Methods: Eight hundred and six patients were recruited from 8 different hospitals. Each clinical research group included 100 patients (50 plant food-allergic patients and 50 pollen-allergic patients). Diagnosis of pollen allergy was based on typical case history of pollen allergy and positive skin prick tests. Diagnosis of plant-food allergy was based on clear history of plant-food allergy, skin prick tests and/or plant-food challenge tests. A panel of 28 purified allergens from pollens and/or plant foods was used to quantify specific IgE (ADVIA-Centaur® platform)., Results: Six hundred and sixty eight patients (83%) of the 806 evaluated had pollen allergy: 396 patients with pollen allergy alone and 272 patients with associated food and pollen allergies. A comparison of both groups showed a statistically significant increase in the food and pollen allergy subgroup in frequency of: (1) asthma (47 vs. 59%; p < 0.001); (2) positive skin test results to several pollens: Plantago, Platanus, Artemisia, Betula, Parietaria and Salsola (p < 0.001); (3) sensitization to purified allergens: Pru p 3, profilin, Pla a 1 - Pla a 2, Sal k 1, PR-10 proteins and Len c 1., Conclusion: Results showed relevant and significant differences between both groups of pollen-allergic patients depending on whether or not they suffered from plant-derived food allergy., (Copyright © 2010 S. Karger AG, Basel.)

According to the recently revised nomenclature for allergy the term "Food Hypersensitivity" is proposed to define a reaction on food exposure causing objectively reproducible symptoms or signs at a dose tolerated by normal subjects. Those reactions to food in which immunologic mechanisms are demonstrated comprise the term "Food Allergy". Immunologic reactions to food in which an immunoglobulin E (IgE)-mediated mechanism is established are defined as IgE-mediated food allergy. This review focuses on IgE-mediated allergic reactions to foods.