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Notes: Background: Mustard allergy accounts for 1.1% of food allergies in children. However, double-blind placebo-controlled food challenge trials (DB PCFCs) have not yet been proposed.Objective: To carry out DB PCFCs to determine the real frequency of mustard allergy in patients sensitized to mustard.Methods: A prospective study was conducted in 30 subjects aged 3–20 years presenting positive prick tests to ground mustard seeds (Brassica nigra), mustard flour (B. juncea), metabisulfite-free strong mustard seasoning (B. juncea) and a commercialized allergenic extract (B. nigra). Twenty-seven subjects were screened for mustard-specific immunoglobulin E (IgE). PCFCs were carried out either DB or single blind (SB) with up to 1340 mg of metabisulfite-free seasoning.Results: The mean diameter of the wheal induced by prick tests with the allergenic extract was lower (n.s.) than that induced by the native mustard products: 5.8 mm (1.5–15) vs 6.9 mm (0.5–18) for B. nigra ground seeds, 7.8 mm (1–20) for B. juncea flour and 9.7 mm (3–20) for the strong mustard seasoning. The diameter of the wheal induced by the allergenic extract was significantly different from that induced by the mustard seasoning (P 〈 0.005). The mean of mustard specific-IgE values was 8.7 KU/l (0.35–72.4). Seven of 30 food challenges were considered positive. Mean prick test results in the positive and negative PCFC subgroups were 5.5 mm vs 5.9 mm for the commercialized extract, 10.9 mm vs 5.8 mm for B. nigra ground seeds (P 〈 0.01), 9.9 mm vs 7.1 mm for B. juncea flour (n.s. P 〉 0.25) and 11.5 mm vs 9.1 mm for the metabisulfite-free mustard seasoning (n.s. P 〉 0.1). Mean specific IgE values determined by CAP system radioallergosorbent test (Phadebas Pharmacia) were higher but not significantly so (P 〉 0.25) in the subgroup with mustard allergy (12.3 K/l vs 7.6 KU/l).Conclusions: About 23.3% of the sensitized subjects were allergic to a routine dose of mustard. Positive prick tests and the presence of specific IgE were not predictive. SB PCFC or DB PCFC is required before recommending avoidance diets.

Notes: Background The prevalence of food anaphylaxis due to masked allergens has increased within the last 10 years. Contamination of manufactured products by food allergens is a key concern for food industries.Objective To determine quantities eliciting reactions in patients who have an IgE-dependent food allergy, thanks to standardized oral provocation tests. To evaluate the subsequent levels of sensitivity required for the detection tests of allergens for egg, peanut, milk and sesame.Methods Prick-in-prick tests, Cap system RAST, and single or double-blind placebo-controlled food challenges (SBPCFC or DBPCFC) were performed. The doses of natural food were gradually increased from 5 to 5000 mg for solid food and from 1 to 30 mL for peanut oil, sunflower oil, soy oil and sesame oil.Results Data from 125 positive oral challenges to egg, 103 to peanut, 59 to milk and 12 to sesame seeds were analysed. Haemodynamic modifications were observed in 2%, 3%, 1.7%, and 8% of the oral challenges (OCs) to egg, peanut, milk and sesame, respectively. Respiratory symptoms were observed in 12%, 20%, 10% and 42% of egg, peanut milk and sesame allergies, respectively. A cumulative reactive dose inferior or equal to 65 mg of solid food or 0.8 mL of milk characterized 16%, 18%, 5% and 8% of egg, peanut, milk and sesame allergies, respectively. 0.8% of egg allergies, 3.9% of peanut allergies, and 1.7% of milk allergies reacted to 10 mg or less of solid food or to 0.1 mL for milk. The lowest reactive threshold has been observed at less than 2 mg of egg; 5 mg of peanut, 0.1 mL of milk and 30 mg of sesame seed. Ten out of 29 OC with peanut oil, two out of two OC with soy oil and three out of six OC with sunflower oil were positive. Five out six OC with sesame oil were positive: 1 and 5 mL induced an anaphylactic shock.Conclusion The risk of asthma and anaphylactic shock to sesame and peanut is confirmed. Minimal reactive quantities show that, in order to guarantee a 95% safety for patients who are allergic to egg, peanut and milk, and on the basis of consumption of 100 g of food, the detection tests should ensure a sensitivity of 10 p.p.m. for egg, 24 p.p.m. for peanut and 30 p.p.m. for milk proteins. Oil allergies being considered, the limit of sensitivity should fall to 5 p.p.m.

Notes: Background Allergy to sesame seeds is often associated with particularly severe reactions, with a high risk of anaphylaxis. The increase in reports of allergic reactions to sesame is probably due to the growing use of sesame seeds or sesame oil in food.Objective To determine the molecular weights of the proteins in three variety of sesame seeds and to study the isoelectric points and the allergenicity of white sesame proteins.Methods Extracts of white, brown and black sesame seeds were prepared. The white sesame extract, mostly used in bakery, was run on SDS-PAGE and two dimensional electrophoresis. Six sera from patients sensitized or symptomatic to sesame seed were used for Western blotting.Results The protein patterns of the white, brown and black sesame extracts showed major quantitative differences. The white extract had the higher protein concentration and contained 15 proteins of 12–79 kDa, some of them having several acidic isoelectric points. The lowest isoelectric point was 4.9 and the highest was 6.4, giving 35 isoforms. Ten of the 15 proteins (12–57.5 kDa) were recognized by specific IgE. The 12–13 kDa and 22–33 kDa proteins could correspond to the main allergens.Conclusion White sesame seeds contain at least 10 allergenic proteins with acidic isoelectric points. In accordance with previous results, two of them seem to contain the major allergens.

Notes: Background Cereal-associated allergy is particularly considered a serious problem, because cereals are essential in our daily diet. Wheat proteins are classified into albumins, globulins and prolamins (insoluble gliadins and glutenins).Objectives Our objectives were to study the involvement in food allergy to wheat of these different protein types by using purified fractions and to identify those binding IgE and IgG antibodies.Methods Sera were obtained from 28 patients with food allergy to wheat. Albumins/globulins, gliadins and glutenins were obtained by sequential extraction based on differential solubility; α-, β-, γ- and ω-gliadins and low molecular weight (LMW) and high molecular weight (HMW) glutenin subunits were purified by chromatography. IgE binding to these extracts and fractions were analysed by radioallergosorbent test (RAST), and immunoblotting; IgG binding was detected by enzyme-linked immunosorbent assay (ELISA).Results In RAST, 60% of sera were shown to have specific IgE antibodies against α-, β-gliadins and LMW glutenin subunits, 55% to γ-gliadins, 48% to ω-gliadins and 26% to HMW glutenins. Immunoblotting analysis confirmed results obtained in RAST concerning LMW and HMW glutenin subunits and showed that 67% of patients have IgE antibodies to the albumin/globulin fraction.Conclusion Results obtained in the different tests showed common features and in agreement with other studies indicated the presence of numerous allergens in food allergy to wheat; α-, β-, γ- and ω-gliadins, LMW glutenin subunits and some water/salt-soluble proteins appeared as major IgE binding allergens, whereas HMW glutenins were only minor allergens. The same type of antigenic profile against gliadins and glutenins was observed with IgG antibodies. Important sequence or structural homologies between the various gliadins and LMW glutenin subunits could certainly explain similarity of IgE binding to these proteins.

Notes: Peanut-containing food products may induce severe clinical reactions in sensitized subjects, and high levels of antipeanut IgE have been reported in the literature. Immunotherapy, proposed for the prevention of severe accidents, is often ill-tolerated and only partly efficient. This could be due to the spontaneous development of polyisotypic antipeanut antibodies.〈section xml:id="abs1-2"〉〈title type="main"〉ObjectiveTo appreciate the presence and reactivity of other isotypes other than IgE of peanut-specific antibodies in serum samples from peanut-sensitized subjects.〈section xml:id="abs1-3"〉〈title type="main"〉MethodsSerum samples were obtained from 20 non-sensitized subjects and 23 sensitized patients divided in three groups according to their response to peanut oral challenge (no response or response to high or low doses, respectively). Peanut-specific IgG, IgG subclasses, IgA and IgM were assayed using an ELISA, and their reactivity against peanut proteins tested using Western Blot.〈section xml:id="abs1-4"〉〈title type="main"〉ResultsA large dispersion of antipeanut antibody levels was observed in the three groups of patients, high levels of IgG, IgG1, IgG4 and IgA usually correlating with highly positive radioallergosorbent test (RAST). Such high levels were observed at onset in four patients who underwent peanut immunotherapy who had side effects and poor efficiency. Western blotting demonstrated that the polyisotypic response observed was directed to several peanut antigens, including the major allergens, Ara h1 and Ara h2.〈section xml:id="abs1-5"〉〈title type="main"〉ConclusionPeanut-sensitized patients who spontaneously develop specific IgE, display polyisotypic-specific antibody responses, whatever their response to oral challenge. This might explain the poor efficiency of peanut rush immunotherapy attempts.