Wang, F., J.M. Robotham, S.S. Teuber, S.K. Sathe, K.H. Roux, 2003. Ana o 2, a major cashew (Anacardium occidentale L.) nut allergen of the legumin family. Int Arch Allergy Immunol. 132:27–39.
Background: We recently cloned and described a vicilin and showed it to be a major cashew allergen. Additional IgE-reactive cashew peptides of the legumin group and 2S albumin families have also been reported. Here, we attempt to clone, express and characterize a second major cashew allergen. Methods: A cashew cDNA library was screened with human IgE and rabbit IgG anticashew extract antisera, and a reactive nonvicilin clone was sequenced and expressed as a fusion protein in Escherichia coli. Immunoblotting was used to screen for reactivity with patients’ sera, and inhibition of immunoblotting was used to identify the corresponding native peptides in cashew nut extract. The identified allergen was subjected to linear epitope mapping using SPOTs solid-phase synthetic peptide technology. Results: Sequence analysis showed the selected clone, designated Ana o 2, to encode for a member of the legumin family (an 11S globulin) of seed storage proteins. By IgE immunoblotting, 13 of 21 sera (62%) from cashew-allergic patients were reactive. Immunoblot inhibition data showed that the native Ana o 2 constitutes a major band at approximately 33 kD and a minor band at approximately 53 kD. Probing of overlapping synthetic peptides with pooled human cashew-allergic sera identified 22 reactive peptides, 7 of which gave strong signals. Several Ana o 2 epitopes were shown to overlap those of the peanut legumin group allergen, Ara h 3, in position but with little sequence similarity. Greater positional overlap and identity was observed between Ana o 2 and soybean glycinin epitopes. Conclusions: We conclude that this legumin-like protein is a major allergen in cashew nut.
Akkerdaas, J.H., M. Wensing, A.C. Knulst, M. Krebitz, H. Breiteneder, S. de Vries, A.H. Penninks, R.C. Aalberse, S.L. Hefle, R. van Ree, 2003. How accurate and safe is the diagnosis of hazelnut allergy by means of commercial skin prick test reagents? Int Arch Allergy Immunol. 132:132–140.
Background: Allergy to tree nuts, like hazelnuts, ranks among the most frequently observed food allergies. These allergies can start at early childhood and are, in contrast to other food allergies, not always outgrown by the patient. Tree nut allergy is frequently associated with severe reactions. Diagnosis partially relies on in vivo testing by means of a skin prick test (SPT) using commercially available SPT reagents. Methods: Protein and allergen composition of nine commercial SPT solutions was evaluated using standard protein detection methods and specific immunoassays for measurement of five individual allergens. Diagnostic performance was assessed by SPT in 30 hazelnut-allergic subjects, of which 15 were provocation proven. Results: Protein concentrations ranged from 0.2–14 mg/ml. SDS-PAGE/silver staining revealed clear differences in protein composition. The major allergen Cor a 1 was present in all extracts but concentrations differed up to a factor 50. An allergen associated with severe symptoms, Cor a 8 (lipid transfer protein), was not detected on immunoblot in three products, and concentrations varied by more than a factor 100 as was shown by RAST inhibition. Similar observations were made for profilin, thaumatin-like protein and a not fully characterized 38-kD allergen. Ratios of individual allergens were variable among the nine extracts. SPT showed significant difference, and 6/30 patients displayed false-negative results using 3/9 products. Conclusion: Variability in the composition of products for the diagnosis of hazelnut allergy is extreme. Sometimes, allergens implicated in severe anaphylaxis are not detected by immunoblotting. These shortcomings in standardization and quality control can potentially cause a false-negative diagnosis in subjects at risk of severe reactions to hazelnuts.
Sicherer, S.H., A. Munoz-Furlong, H.A. Sampson, 2003. Prevalence of peanut and tree nut allergy in the United States determined by means of a random digit dial telephone survey: A 5 year follow-up. J Allergy Clin Immunol. 112:1203-1207.
Background: Allergy to peanuts and tree nuts (TNs) is the leading cause of fatal and near-fatal food allergic reactions. Peanut allergy appears to be increasing in prevalence. Objectives: We sought to determine the prevalence of self-reported peanut and TN allergy among the general population of the United States in 2002 by sex and age and to compare the results with prevalence estimates obtained 5 years earlier. Methods: We performed a nationwide, cross-sectional, random telephone survey by using a standardized questionnaire. Results: A total of 4855 households participated (53% participation rate), representing a census of 13,493 individuals. Peanut allergy, TN allergy, or both was self-reported in 166(1.2%; 95% CI, 1.0%-1.4%) individuals in 155 (3.2%; 95% CI, 2.7%-3.7%) households, overall prevalence rates similar to those reported in 1997. Also similar to the 1997 survey, the severity level was high, with 79% reporting respiratory or multiple organ system reactions and 66% experiencing more than 5 lifetime reactions. Despite the severity and reaction frequency, only 74% of the children and 44% of the adults sought evaluation for the allergy, and fewer than half who did were prescribed self-injectable epinephrine. Applying conservative rules to adjust for persons with unconvincing reactions and a false-positive rate of the survey instrument (7%), a final prevalence estimate of 1.04% (95% CI, 0.9%-1.24%) was obtained. A male predominance of peanut-TN allergy was reported in children younger than 18 years (1.7% vs 0.7%, P = .02), and a female predominance was reported among adults (1.7% vs 0.9%, P = .0008). Although the rate of peanut allergy, TN allergy, or both was not significantly different from 1997 to 2002 among adults, the rate increased from 0.6% to 1.2% among children, primarily as a result of an increase in reported allergy to peanut (0.4% in 1997 to 0.8% in 2002, P = .05). Conclusions: Self-reported peanut allergy has doubled among children from 1997 to 2002, and peanut allergies, TN allergies, or both continue to be reported by more than 3 million Americans. Considering that reactions are severe and the allergy is persistent, these allergies represent an increasing health concern.
Teuber, S.S., S.K. Sathe, W.R. Peterson, K.H. Roux, 2002. Characterization of the soluble allergenic proteins of cashew nut (Anacardium occidentale L.). J Agric Food Chem. 50(22):6543-6549.
The allergens associated with cashew food allergy have not been well-characterized. We sought to identify the major allergens in cashew nut by performing IgE immunoblots to dissociated and reduced or nonreduced cashew protein extracts, followed by sequencing of the peptides of interest. Sera from 15 subjects with life-threatening reactions to cashews and 8 subjects who tolerate cashews but have life-threatening reactions to other tree nuts were compared. An aqueous cashew protein extract containing albumin/globulin was separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and subjected to IgE immunoblotting using patient sera. Selected IgE reactive bands were subjected to N-terminal amino acid sequencing. Each of the 15 sera from cashew-allergic subjects showed IgE binding to the cashew protein extract. The dominant IgE-binding antigens in the reduced preparations included peptides in the 31-35 kD range, consistent with the large subunits of the major storage 13S globulin (legumin-like protein). Low-molecular-weight polypeptides of the 2S albumin family, with similarity to the major walnut allergen Jug r 1, also bound IgE. The sera from eight patients who tolerate cashew but displayed allergies to other tree nuts showed only minimal or no IgE binding to cashew. Cashew food allergy is associated with the presence of IgE directed against the major seed storage proteins in cashew, including the 13S globulin (legumin group) and 2S albumins, both of which represent major allergen classes in several plant seeds. Thus, the legumin-group proteins and 2S albumins are again identified as major food allergens, which will help further research into seed protein allergenicity.
Añó, M.A., J.P. Maselli, M.L. Sanz, M. Fernández-Benítez, 2002. Allergy to pine nut. Allergol Immunopathol (Madr). 30(2):104-108.
Background:food allergy is highly prevalent in our environment, especially among atopic patients. Pinus pinea is common in our region and its fruit, the pine nut, is allergologically important. Several cases have been reported in the literature that demonstrate the existence of common antigenic bands between pine nut and almond. In this study we try to assess this finding and the possible existence of common allergens by in vitro techniques. Methods and results:we present a 10-year-old boy, previously diagnosed of seasonal rhinoconjunctivitis with sensitisation to grass and olive pollen, who had an anaphylactic reaction after eating pine nut. We performed in vivo (prick test, prick-by-prick) and in vitro tests (total and specific IgE determinations [CAP-FEIA]), histamine release test, and immunoblotting (SDS-PAGE). We also reviewed the literature through the MEDLINE database in PubMed. Conclusions:because pine nut is commonly consumed in our environment, the prevalence of allergic reactions is probably considerable and these reactions take place at an early age. We demonstrate the existence of common antigenic proteins between pine nut and peanuts.
Poltronieri. P., M.S. Cappello, N. Dohmae, A. Conti, D. Fortunato, E.A. Pastorello, C. Ortolani, G. Zacheo, 2002. Identification and characterisation of the IgE-binding proteins 2S albumin and conglutin γ in almond (Prunus dulcis) seeds. Int Arch Allergy Immunol. 128:97–104.
Background: Almond proteins can cause severe anaphylactic reactions in susceptible individuals. The aim of this study was the identification of IgE-binding proteins in almonds and the characterisation of these proteins by N-terminal sequencing. Methods: Five sera were selected from individuals with a positive reaction to food challenge. Sodium dodecylsulphate-polyacrylamide gel electrophoresis and immunoblotting were performed on almond seed proteins. Purified IgE-binding proteins were tested for immunoblot inhibition with sera preincubated with extracts of hazelnut and walnut. Results: N-terminal sequences of the 12-, 30- and 45-kD proteins were obtained. The 45- and 30-kD proteins shared the same N terminus, with 60% homology to the conglutin γ heavy chain from lupine seed (Lupinus albus) and to basic 7S globulin from soybean (Glycine max). The sequences of the N-terminal 12-kD protein and of an internal peptide obtained by endoproteinase digestion showed good homology to 2S albumin from English walnut (Jug r 1). Immunoblot inhibition experiments were performed and IgE binding to almond 2S albumin and conglutin γ was detected in the presence of cross-reacting walnut or hazelnut antigens. Conclusions: Two IgE-binding almond proteins were N-terminally sequenced and identified as almond 2S albumin and conglutin γ. Localisation and conservation of IgE binding in a 6-kD peptide obtained by endoproteinase digestion of 2S albumin was shown.
Bindslev-Jensen, C., D. Briggs, M. Osterballe, 2002. Can we determine a threshold level for allergenic foods by statistical analysis of published data in the literature? Allergy. 57: 741–746.
Background: The aim of this paper was to investigate whether a statistical model could be developed to estimate a ‘‘threshold’’ dose for foods eliciting allergic reactions in susceptible patients. The threshold dose is defined to be one that elicits allergic reactions in a given (small) proportion of susceptible patients, using data from published studies. Methods: Based on data available from the literature, we developed a statistical model using the actual allergen content in the four foods, where data for allergen content are available (peanut, soy, egg, milk). Results: The model demonstrated that the threshold doses giving a reaction of one in a million in susceptible patients were within the same order of magnitude for egg, milk and soy, but were an order of magnitude lower for peanut flour: 0.005 mg of cow’s milk, 0.002 mg of fresh hen’s egg, 0.0007 mg of peanut, or 0.0013 mg of soy flour. Conclusions: Although several assumptions were made in creating this statistical model, we demonstrated that the previously published differences in threshold doses for various foods can be largely eliminated by comparing actual allergen content; this may therefore serve as a model for further studies.
Pastorello, E.A., S. Vieths, V. Pravettoni, L. Farioli, C. Trambaioli, D. Fortunato, D. Lüttkopf, M. Calamari, R. Ansaloni, J. Scibilia, B.K. Ballmer-Weber, L.K. Poulsen, B. Wütrich, K.S. Hansen, A.M. Robino, C. Ortolani, A. Conti, 2002. Identification of hazelnut major allergens in sensitive patients with positive double-blind, placebo-controlled food challenge results. J Allergy Clin Immunol. 109:563-570.
Background: The hazelnut major allergens identified to date are an 18-kd protein homologous to Bet v 1 and a 14-kd allergen homologous to Bet v 2. No studies have reported hazelnut allergens recognized in patients with positive double-blind, placebo-controlled food challenge (DBPCFC) results or in patients allergic to hazelnut but not to birch. Objective: We characterized the hazelnut allergens by studying the IgE reactivity of 65 patients with positive DBPCFC results and 7 patients with severe anaphylaxis to hazelnut. Methods: Hazelnut allergens were identified by means of SDSPAGE and IgE immunoblotting. Further characterization was done with amino acid sequencing, evaluation of the IgE-binding properties of raw and roasted hazelnut with enzyme allergosorbent test inhibition, assessment of cross-reactivity with different allergens by means of immunoblotting inhibition, and purification by means of HPLC. Results: All the sera from the patients with positive DBPCFC results recognized an 18- and a 47-kd allergen; other major allergens were at molecular weights of 32 and 35 kd. Binding to the 18-kd band was inhibited by birch extract, indicating its homology with the birch major allergen, and abolished in roasted hazelnut. The 47-kd allergen is a sucrose-binding protein, the 35-kd allergen is a legumin, and the 32-kd allergen is a 2S albumin. Patients with severe anaphylactic reactions to hazelnut showed specific IgE reactivity to a 9-kd allergen, totally inhibited by purified peach lipid-transfer protein (LTP), which was heat stable and, when purified, corresponded to an LTP. Conclusions: The major allergen of hazelnut is an 18-kd protein homologous to Bet v 1, and the 9-kd allergen is presumably an LTP. Other major allergens have molecular weights of 47, 32, and 35 kd.
Wigotzki, M., H. Steinhart, A. Paschke, 2001. Determination of the allergenicity of various hazelnut products by immunoblotting and enzyme allergosorbent test inhibition. Journal of Chromatography B. 756:239–248.
Although allergic reactions to hazelnuts are common especially in Europe, there are only a few investigations with regard to the influence of processing on the IgE-binding potency of hazelnut proteins. In this study the allergenicity of different hazelnut products, such as chocolate, nougat products, croquant or cookies, was examined by sodium dodecyl sulfate– polyacrylamide gel electrophoresis (SDS–PAGE), immunoblotting and enzyme allergosorbent test (EAST) inhibition experiments using sera of 17 hazelnut-allergic individuals. In only a few cases did the immunoblotting experiments yield positive results as regards the allergenicity of the investigated products. By means of EAST inhibition a residual IgE-binding potency could be detected in almost all of the product extracts. Therefore hazelnuts are a potential hazard to allergic people even as an ingredient of processed foods.
Background: A voluntary registry of individuals with peanut and/or tree nut allergy was established in 1997 to learn more about these food allergies. Objective: The purpose of this study was to elucidate a variety of features of peanut and tree nut allergy among the first 5149 registry participants. Methods: The registry was established through use of a structured questionnaire distributed to all members of the Food Allergy and Anaphylaxis Network and to patients by allergists. Parental surrogates completed the forms for children under the age of 18 years. Results: Registrants were primarily children (89% of registrants were younger than 18 years of age; the median age was 5 years), reflecting the membership of the Network. Isolated peanut allergy was reported by 3482 registrants (68%), isolated tree nut allergy by 464 (9%), and allergy to both foods by 1203 (23%). Registrants were more likely to have been born in October, November, or December (odds ratio, 1.2; 95% CI, 1.18-1.23; P < .0001). The median age of reaction to peanut was 14 months, and the median age of reaction to tree nuts was 36 months; these represented the first known exposure for 74% and 68% of registrants, respectively. One half of the reactions involved more than 1 organ system, and more than 75% required treatment, frequently from medical personnel. Registrants with asthma were more likely than those without asthma to have severe reactions (33% vs 21%; P < .0001). In comparison with initial reactions, subsequent reactions due to accidental ingestion were more severe, more common outside the home, and more likely to be treated with epinephrine. Conclusions: Allergic reactions to peanut and tree nut are frequently severe, often occur on the first known exposure, and can become more severe over time.
