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Background: Celery root is known to cause severe allergic reactions in patients sensitized to mugwort pollen., Objective: We studied clinically well-characterized patients with celery allergy by IgE testing with a comprehensive panel of celery allergens to disentangle the molecular basis of what is known as the celery-mugwort syndrome., Methods: Patients with suspected food allergy to celery underwent a standardized interview. Main inclusion criteria were a positive food challenge with celery or an unambiguous case history of severe anaphylaxis. IgE to celery allergens (rApi g 1.01, rApi g 1.02, rApi g 2, rApi g 4, nApi g 5, rApi g 6, rApi g 7) and to mugwort allergens (rArt v 1, rArt v 3, rArt v 4) were determined. IgE levels ≥0.35 kU A /L were regarded positive., Results: Seventy-nine patients with allergy to celery were included. Thirty patients had mild oral or rhinoconjunctival symptoms, and 49 had systemic reactions. Sixty-eight percent had IgE to celery extract, 80% to birch pollen, and 77% to mugwort pollen. A combination of Api g 1.01, 1.02, 4, 5, and 7 increased the diagnostic sensitivity for celery allergy to 92%. The lipid transfer proteins Api g 2 and Api g 6 were not relevant in our celery-allergic population. IgE to Api g 7, detected in 52% of patients, correlated closely (r = 0.86) to Art v 1 from mugwort pollen. Eleven of 12 patients with monosensitization to Api g 7 were IgE negative to celery extract. The odds ratio for developing a severe anaphylactic reaction rather than only mild oral symptoms was about 6 times greater (odds ratio, 5.87; 95% confidence interval, 1.08-32.0; P = .0410) for Api g 7-sensitized versus -nonsensitized subjects., Conclusion: There is an urgent need for routine diagnostic tests to assess sensitization to Api g 7, not only to increase test sensitivity but also to identify patients at risk of a severe allergic reaction to celery., (Copyright © 2024 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Food allergies are a significant public health issue, and the only effective management option currently available is strict avoidance of all foods containing the allergen. In view of the practical impossibility of limiting risks to zero, quantitative allergen risk assessment and management strategies are needed., Objective: We sought to develop appropriate methods for informing population-based risk assessments and risk management programs to benefit all stakeholders but particularly patients with food allergy., Methods: Individual thresholds for food allergens (maximum tolerable doses and minimum eliciting doses) can ideally be established through double-blind, placebo-controlled food challenges. If double-blind, placebo-controlled food challenge data are not available, data from widely used open food challenges using predefined objective criteria can also provide useful data regarding minimum eliciting doses. For more than 20 years, the Netherlands Organisation for Applied Scientific Research and the Food Allergy Research and Resource Program at the University of Nebraska-Lincoln have been collecting individual maximum tolerable doses and minimum eliciting doses that produce objective symptoms from published and unpublished clinical data to better refine knowledge regarding the sensitivity of the population to food allergens., Results: In this article we provide in-depth insights into the methodology applied by the Netherlands Organisation for Applied Scientific Research and Food Allergy Research and Resource Program to derive individual maximum tolerable doses and minimum eliciting doses for objective symptoms from clinical food challenge data. More than 90 examples for determining individual allergic thresholds are presented., Conclusion: With the methodology presented in this article, we aim to stimulate harmonization and transparency in quantitative food allergen risk assessment and risk management programs, encouraging their wider adoption., (Copyright © 2019 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Hazelnut allergy is birch pollen-driven in Northern/Western Europe and lipid transfer protein-driven in Spain and Italy. Little is known about other regions and other allergens., Objective: Establishing a molecular map of hazelnut allergy across Europe., Methods: In 12 European cities, subjects reporting reactions to hazelnut (n = 731) were evaluated and sensitization to 24 foods, 12 respiratory allergen sources, and latex was tested by using skin prick test and ImmunoCAP. A subset (124 of 731) underwent a double-blind placebo-controlled food challenge to hazelnut. Sera of 423 of 731 subjects were analyzed for IgE against 7 hazelnut allergens and cross-reactive carbohydrate determinants by ImmunoCAP., Results: Hazelnut allergy was confirmed in 70% of those undergoing double-blind placebo-controlled food challenges. Birch pollen-driven hazelnut sensitization (Cor a 1) dominated in most cities, except in Reykjavik, Sofia, Athens, and Madrid, where reporting of hazelnut allergy was less frequent anyhow. In Athens, IgE against Cor a 8 dominated and strongly correlated with IgE against walnut, peach, and apple and against Chenopodium, plane tree, and mugwort pollen. Sensitization to seed storage proteins was observed in less than 10%, mainly in children, and correlated with IgE to nuts, seeds, and legumes. IgE to Cor a 12, observed in all cities (10% to 25%), correlated with IgE to nuts, seeds, and pollen., Conclusions: In adulthood, the importance of hazelnut sensitization to storage proteins, oleosin (Cor a 12), and Cor a 8 is diluted by the increased role of birch pollen cross-reactivity with Cor a 1. Cor a 8 sensitization in the Mediterranean is probably driven by diet in combination with pollen exposure. Hazelnut oleosin sensitization is prevalent across Europe; however, the clinical relevance remains to be established., (Copyright © 2015 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Precautionary labeling is used to warn consumers of the presence of unintended allergens, but the lack of agreed allergen thresholds can result in confusion and risk taking by patients with food allergy. The lack of data on threshold doses below which subjects are unlikely to react is preventing the development of evidence-based allergen management strategies that are understood by clinician and patient alike., Objective: We sought to define threshold dose distributions for 5 major allergenic foods in the European population., Methods: Patients with food allergy were drawn from the EuroPrevall birth cohort, community surveys, and outpatient clinic studies and invited to undergo a food challenge. Low-dose, double-blind, placebo-controlled food challenges were undertaken with commercially available food ingredients (peanut, hazelnut, celery, fish, and shrimp) blinded into common matrices. Dose distributions were modeled by using interval-censoring survival analysis with 3 parametric approaches., Results: Of the 5 foods used for challenge, 4 produced similar dose distributions, with estimated doses eliciting reactions in 10% of the allergic population (ED10), ranging from 1.6 to 10.1 mg of protein for hazelnut, peanut, and celery with overlapping 95% CIs. ED10 values for fish were somewhat higher (27.3 mg of protein), although the CIs were wide and overlapping between fish and plant foods. Shrimp provided radically different dose distributions, with an ED10 value of 2.5 g of protein., Conclusion: This evidence base will contribute to the development of reference doses and action levels for allergens in foods below which only the most sensitive subjects might react., (Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Kiwifruit is a common cause of food allergy. Symptoms range from mild to anaphylactic reactions., Objective: We sought to elucidate geographic differences across Europe regarding clinical patterns and sensitization to kiwifruit allergens. Factors associated with the severity of kiwifruit allergy were identified, and the diagnostic performance of specific kiwifruit allergens was investigated., Methods: This study was part of EuroPrevall, a multicenter European study investigating several aspects of food allergy. Three hundred eleven patients with kiwifruit allergy from 12 countries representing 4 climatic regions were included. Specific IgE to 6 allergens (Act d 1, Act d 2, Act d 5, Act d 8, Act d 9, and Act d 10) and kiwifruit extract were tested by using ImmunoCAP., Results: Patients from Iceland were mainly sensitized to Act d 1 (32%), those from western/central and eastern Europe were mainly sensitized to Act d 8 (pathogenesis-related class 10 protein, 58% and 44%, respectively), and those from southern Europe were mainly sensitized to Act d 9 (profilin, 31%) and Act d 10 (nonspecific lipid transfer protein, 22%). Sensitization to Act d 1 and living in Iceland were independently and significantly associated with severe kiwifruit allergy (odds ratio, 3.98 [P = .003] and 5.60 [P < .001], respectively). Using a panel of 6 kiwifruit allergens in ImmunoCAP increased the diagnostic sensitivity to 65% compared with 20% for skin prick tests and 46% ImmunoCAP using kiwi extract., Conclusion: Kiwifruit allergen sensitization patterns differ across Europe. The use of specific kiwifruit allergens improved the diagnostic performance compared with kiwifruit extract. Sensitization to Act d 1 and living in Iceland are strong risk factors for severe kiwifruit allergy., (Copyright © 2012 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Background: Patients with birch pollen allergy often develop allergic reactions to plant foods., Objective: To evaluate the prevalence, main symptoms, and triggers of birch pollen-related food allergy and the role of food-specific IgG(4) antibodies in food tolerance., Methods: Food-induced symptoms were evaluated in 225 individuals with birch pollen allergy by using a standardized questionnaire. IgE and IgG(4) levels specific for the major birch pollen allergen Bet v 1 and birch profilin Bet v 2 and the Bet v 1 homologs in apple (Mal d 1) and hazelnut (Cor a 1) were quantified by ImmunoCAP. Mock-treated and IgG-depleted sera from patients tolerating hazelnuts in food challenges were compared for their inhibitory activity for binding of Cor a 1-IgE complexes to B cells., Results: In total, 73% of the study population experienced food allergy, which was perennial in 86% of the affected individuals. The oral allergy syndrome was the main clinical manifestation. However, more than 58% of the patients also experienced food-induced rhinoconjunctivitis. Apples and hazelnuts were identified as the most frequent triggers. Food allergy correlated with IgE reactivity to Bet v 1 but not to Bet v 2. Mal d 1-specific and Cor a 1-specific IgG(4)/IgE ratios were significantly higher in food-tolerant individuals than individuals with food allergy. Sera from IgG(4)-positive food-tolerant patients possessed IgG-dependent IgE-inhibitory activity., Conclusion: Birch pollen-related food allergy is highly prevalent and often perennial. High food allergen-specific IgG(4)/IgE ratios seem associated with food tolerance, potentially because specific IgG(4) blocks IgE binding to food allergens. Thus, the presence of food allergen-specific IgG(4) antibodies is no diagnostic marker for birch pollen-related food allergy., (Copyright © 2011 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Background: Kiwifruit is one of the most common causes of food allergic reactions. Component-resolved diagnostics may enable significantly improved detection of sensitization to kiwifruit., Objective: To evaluate the use of individual allergens for component-resolved in vitro diagnosis of kiwifruit allergy., Methods: Thirty patients with a positive double-blind placebo-controlled food challenge to kiwifruit, 10 atopic subjects with negative open provocation to kiwifruit, and 5 nonatopic subjects were enrolled in the study. Specific IgE to 7 individual allergens (nAct d 1-5 and rAct d 8-9) and allergen extracts was measured by ImmunoCAP., Results: The diagnostic sensitivities of the commercial extract and of the sum of single allergens were 17% and 77%, respectively, whereas diagnostic specificities were 100% and 30%. A combination of the kiwi allergens Act d 1, Act d 2, Act d 4, and Act d 5 gave a diagnostic sensitivity of 40%, whereas diagnostic specificity remained high (90%). Exclusion of the Bet v 1 homolog recombinant (r) Act d 8 and profilin rAct d 9 from this allergen panel reduced sensitivity to 50% but increased specificity to 40%. Kiwifruit-monosensitized patients reacted more frequently (P < .001) with Act d 1 than polysensitized patients, whereas the latter group reacted more frequently with rAct d 8 (P = .004)., Conclusion: Use of single kiwifruit allergen ImmunoCAP increases the quantitative test performance and diagnostic sensitivity compared with the commercial extract. Bet v 1 homolog and profilin are important allergens in pollen-related kiwifruit allergy, whereas actinidin is important in monoallergy to kiwifruit, in which symptoms are often more severe.

Background: Previous studies have demonstrated insufficient sensitivity of commercially available celeriac extract reagents in the diagnosis of celeriac allergy., Objective: We sought to assess the diagnostic performance of specific IgE determination based on recombinant and purified natural celeriac allergens in comparison with an extract-based assay and to investigate interference by IgE to cross-reactive carbohydrate determinants and its biologic activity., Methods: Twenty-four subjects with a positive double-blind, placebo-controlled food challenge result to celeriac; 20 atopic control subjects with birch pollen allergy who tolerated celeriac; and 20 nonatopic subjects were enrolled. IgE binding was investigated for celeriac allergens (rApi g 1.01, rApi g 4, and nApi g 5), extract reagents (celeriac, birch, mugwort, and timothy grass pollen), birch pollen allergens (rBet v 1 and rBet v 2), and cross-reactive carbohydrate determinants by means of ImmunoCAP analysis. Biologic activity of allergens was determined based on basophil mediator release., Results: Component-resolved ImmunoCAP analysis considerably increased the sensitivity to detect celeriac-specific IgE by 20%. Sensitization to carbohydrate structures was detected in 38% of patients with celeriac allergy, and there was an excellent correlation between sensitization to the glycoprotein Api g 5 and isolated glycan. Positive results among atopic control subjects were mainly caused by protein allergens, whereas the effect of carbohydrate epitopes was marginal. The ability of allergens to induce mediator release decreased in the order Bet v 1 > Api g 1 > Api g 5, confirming the low biologic activity of IgE to carbohydrate epitopes., Conclusion: Component-resolved diagnosis allowed an increase in diagnostic sensitivity from 67% to 88% compared with extract-based diagnosis. Sensitization to Api g 5 was attributable to its glycan moieties but did not interfere with diagnostic specificity.

Background: Analysis of IgE antibody binding to epitopes provides information for food allergy diagnosis and management and construction of hypoallergenic candidate vaccines, but the contribution of sequential epitopes to functionally relevant IgE binding is not fully understood., Objectives: We sought to study the impact of IgE-binding peptides described as major sequence epitopes in the literature on IgE-binding capacity of 2 selected food allergens., Methods: IgE-binding peptides of the food allergens Ara h 2 (peanut) and Pen a 1 (shrimp) were identified. Synthetic soluble peptides representing the identified sequences were assessed for their capacity to inhibit IgE binding to the parent allergens by means of ELISA and in mediator release assay. The IgE-binding capacity of unfolded recombinant (r) Ara h 2 was analyzed. A hybrid tropomyosin carrying the IgE-binding regions of Pen a 1 grafted into the structural context of the nonallergenic mouse tropomyosin was applied in ELISA inhibition experiments and ImmunoCAP analysis., Results: Although IgE-binding peptides representing sections of the allergen sequences were detected, no relevant capacity to inhibit the IgE binding to the parent allergen in ELISA or basophil activation test was observed. Unfolded rAra h 2 showed reduced IgE-binding capacity compared with folded rAra h 2 and failed to elicit mediator release. Hybrid tropomyosin bound less IgE than rPen a 1 in ImmunoCAP analysis and revealed marginal inhibitory capacity., Conclusion: Peptides identified as major sequence epitopes on Pen a 1 and Ara h 2 show little contribution to the IgE binding of the allergens studied.

Background: Food allergy to hazelnut occurs both with and without concomitant pollen allergy., Objective: We sought to evaluate a panel of hazelnut allergens for diagnosis of hazelnut allergy in Spain, Switzerland, and Denmark., Methods: Fifty-two patients with a positive double-blind, placebo-controlled food challenge result with hazelnuts; 5 patients with a history of anaphylaxis; 62 patients with pollen allergy but hazelnut tolerance; and 63 nonatopic control subjects were included. Serum IgE levels to hazelnut extract, recombinant hazelnut allergens (rCor a 1.04, rCor a 2, rCor a 8, rCor a 11), and native allergens (nCor a 9, nCor a Bd8K, nCor a Bd11K) were analyzed by means of ImmunoCAP., Results: Among patients with hazelnut allergy, 91% (Switzerland/Spain, 100%; Denmark, 75%) had IgE to hazelnut extract, 75% to rCor a 1.04, 42% to rCor a 2, 28% to rCor a 8, and 2% to rCor a 11. The highest rate of sensitization to Cor a 1.04 was found in the northern regions (Switzerland/Denmark, 100%; Spain, 18%), whereas IgE to the lipid transfer protein rCor a 8 prevailed in Spain (Spain, 71%; Switzerland, 15%; Denmark, 5%). IgE to profilin rCor a 2 was equally distributed (40% to 45%). Among control subjects with pollen allergy, 61% had IgE to hazelnut extract, 69% to rCor a 1.04, 34% to rCor a 2, 10% to rCor a 8, and 6% to rCor a 11., Conclusion: Component-resolved in vitro analyses revealed substantial differences in IgE profiles of hazelnut allergic and hazelnut tolerant patients across Europe.

Background: Soybean is considered an important allergenic food, but published data on soybean allergens are controversial., Objective: We sought to identify relevant soybean allergens and correlate the IgE-binding pattern to clinical characteristics in European patients with confirmed soy allergy., Methods: IgE-reactive proteins were identified from a soybean cDNA expression library, purified from natural soybean source, or expressed in Escherichia coli. The IgE reactivity in 30 sera from subjects with a positive double-blind, placebo-controlled soybean challenge (n = 25) or a convincing history of anaphylaxis to soy (n = 5) was analyzed by ELISA or CAP-FEIA., Results: All subunits of Gly m 5 (beta-conglycinin) and Gly m 6 (glycinin) were IgE-reactive: 53% (16/30) of the study subjects had specific IgE to at least 1 major storage protein, 43% (13/30) to Gly m 5 , and 36% (11/30) to Gly m 6. Gly m 5 was IgE-reactive in 5 of 5 and Gly m 6 in 3 of 5 children. IgE-binding to Gly m 5 or Gly m 6 was found in 86% (6/7) subjects with anaphylaxis to soy and in 55% (6/11) of subjects with moderate but only 33% (4/12) of subjects with mild soy-related symptoms. The odds ratio (P < .05) for severe versus mild allergic reactions in subjects with specific IgE to Gly m 5 or Gly m6 was 12/1., Conclusion: Sensitization to the soybean allergens Gly m 5 or Gly m 6 is potentially indicative for severe allergic reactions to soy.

This article aims to critically review developments in food allergy diagnostics with regard to the verification of specific IgE antibodies and the identification of the responsible allergens. Results of IgE-binding tests with food extracts are hampered by cross-reactive proteins, low-quality test agents, or both. Specificity can be increased by defining adequate cutoff values, whereas sensitivity can be improved by using high-quality test agents. IgE-binding tests with purified allergens enabled reliable quantification of allergen-specific IgE titers, with higher levels found in individuals with food allergy compared with individuals without food allergy. However, the overlap in individual test reactivity between allergic and nonallergic subjects complicates interpretation. Recombinant allergens and synthetic sequential epitopes enabled detection of sensitization profiles, with IgE specific to several allergens and substructures now being suggested as markers of severity, persistence, or both. However, high-power quantitative studies with larger numbers of patients are required to confirm these markers. IgE-binding tests merely indicate sensitization, whereas the final proof of clinical relevance still relies on family/case history, physical examinations, and provocation tests. Novel technologies promise superior diagnostics. Microarray technology permits simultaneous measurement of multiple IgE reactivities regarding specificity, abundance, reactivity, or interaction. Improved functional tests might enable reliable estimation of the clinical relevance of IgE sensitizations at justifiable expenses.

Background: Soybean is a relevant allergenic food, but little is known about individual threshold doses in soy allergy., Objective: We sought to determine the clinical characteristics of soy allergy in Europe, including a dose-response curve., Methods: Patients with a history of soy allergy underwent a titrated, double-blind, placebo-controlled food challenge. A statistical model was used to calculate the risk of allergic consumers to experience an allergic reaction to soy. Sera were analyzed for specific IgE to soy, peanut, Bet v 1, and Gly m 4., Results: All patients but one responded primarily with subjective symptoms to the challenge followed by objective symptoms in 11 subjects, ranging from rhinitis up to a decrease in blood pressure. Cumulative threshold doses for allergic reactions ranged from 10 mg to 50 g for subjective symptoms and from 454 mg to 50 g for objective symptoms. The pattern of IgE reactivity against proteins with molecular weights of between approximately 10 and 70 kd was highly individual among the patients and did not correlate with the severity of symptoms., Conclusions: When data are fitted by using a normal distribution statistical model, they predict that 1% of patients with soy allergy would react subjectively and objectively with 0.21 and 37.2 mg of soy protein, respectively., Clinical Implications: Both the clinical and immunologic basis of soy allergy in Europe are highly complex, which affects the diagnosis of soy allergy and the advice given to patients with soy allergy in regard to risk management.

Background: Carrot allergy is caused by primary sensitization to birch pollen. Continuous carrot exposure results in additional Dau c 1-specific allergic responses. Thus, immunotherapy with birch pollen may not improve the food allergy., Objective: Evaluation of mutation and oligomerization of the major carrot allergen, Dau c 1, in regard to alteration of antibody binding capacities, structure, and the ability to induce blocking IgG antibodies., Methods: Measurement of IgE reactivities to monomers, dimers of wild-type and mutant Dau c 1.0104 and Dau c 1.0201, and Dau c 1.0104 trimer, their ability to induce blocking antibodies in mice, and their allergenic potency by histamine release., Results: The reactivity of human IgE to the mutant dimer was reduced on average by 81%. Sera of immunized Balb/c mice showed specific IgG similar to the human IgE antibody response; Dau c 1.01 was more antigenic than Dau c 1.02. Both wild-type and mutant Dau c 1 variants induced cross-reacting IgG, which blocked binding of human IgE. The mutants were more antigenic than the wild-type forms, and the dimers induced higher IgG responses in mice than the monomers. The results of the histamine release experiments corroborated the findings of the antibody binding studies., Conclusion: Destruction of native conformation rather than oligomerization is the appropriate strategy to reduce the allergenicity of Bet v 1-homologous food allergens., Clinical Implications: The dimer composed of mutants of Dau c 1.0104 and Dau c 1.0201 is a promising candidate vaccine for treatment of carrot allergy because of its high immunogenicity and drastically reduced allergenicity.

Background: Baker's asthma is a serious problem for a significant proportion of workers in bakeries, confectionaries, and the food industry. Although several wheat allergens related to baker's asthma have been described, standardized reagents for a reliable diagnosis are not yet available., Objective: To clone novel wheat allergens related to baker's asthma and investigate the cross-reactive potential of their maize and human homologues., Methods: A wheat cDNA phage display library was screened with sera from bakers with occupational asthma for IgE-binding structures. Homologous sequences from maize and human thioredoxins were amplified from corresponding cDNA libraries., Results: Within the enriched wheat cDNA repertoire we identified, among others, the sequence encoding wheat thioredoxin-hB (Triticum aestivum allergen 25 [Tri a 25]). The recombinant protein displayed enzymatic activity, and we observed a sensitization rate of 47% among bakers with occupational asthma and of 35% among patients with grass pollen allergy, but without a clinical history of cereal allergy. Furthermore, the previously characterized maize thioredoxin-h1 (Zea mays allergen 25 [Zea m 25]), sharing 74% identity with Tri a 25, exhibited distinct IgE cross-reactivity with its wheat homologue. Two bakers also showed sensitization to human thioredoxin, which shares 29% identity with Tri a 25. In a comparative study, we included recombinant alpha-amylase inhibitor 0.19, showing a sensitization rate of 65% in individuals with baker's asthma., Conclusion: Thioredoxins represent a novel family of cross-reactive allergens that might contribute to the symptoms of baker's asthma and might in addition be related to grass pollen allergy, as indicated by the reactivity of grass pollen allergic patients to cereal thioredoxins., Clinical Implications: The recombinant cereal thioredoxins will, together with the already reported wheat allergens, contribute to a more reliable diagnosis of baker's asthma and, perhaps, become a tool for the development of component-resolved immunotherapy.

Background: We recently described patients with soybean allergy mainly mediated by cross-reactivity to birch pollen allergens. A majority of those patients were reported to have peanut allergy., Objective: We sought to study the occurrence of peanut allergy in patients allergic to birch pollen and characterized the Bet v 1-homologous peanut allergen Ara h 8., Methods: Recombinant Ara h 8 was cloned with degenerated primers and expressed in Escherichia coli. Nine Swiss and 11 Dutch patients with peanut and birch pollen allergy and a positive double-blind, placebo-controlled food challenge result to peanut were investigated for IgE reactivity to birch pollen and purified peanut allergens and cross-reactivity between birch and peanut. Ara h 8 stability against digestion and roasting was assessed by means of RAST inhibition. The IgE cross-linking potency of Ara h 8 was tested on the basis of basophil histamine release., Results: During double-blind, placebo-controlled food challenge, all patients experienced symptoms in the oral cavity, progressing to more severe symptoms in 40% of patients. CAP-FEIA detected recombinant (r) Ara h 8-specific IgE in 85%. IgE binding to Ara h 8 was inhibited by Bet v 1 in peanut extract immunoblotting and in RAST inhibition. In EAST inhibition recombinant rAra h 8 inhibited IgE binding to peanut in 4 of 7 tested patient sera. Antipeanut response was dominated by Ara h 8 in 12 of 17 tested patients. Furthermore, our results demonstrate a low stability of Ara h 8 to roasting and no stability to gastric digestion. Basophil histamine release with rAra h 8 was more than 20% in 5 of 7 tested sera., Conclusions: Peanut allergy might be mediated in a subgroup of our patients by means of cross-reaction of Bet v 1 with the homologous peanut allergen Ara h 8.

Background: Allergic reactions to legumes are generally thought to be acquired by means of primary sensitization through the gastrointestinal tract. Recently, Gly m 4 (starvation-associated message 22), a Bet v 1-related pathogenesis-related protein 10 from soy, was suggested to be an allergen in patients with allergic reactions to a dietary product containing a soy protein isolate., Objective: We sought to evaluate the clinical relevance of Gly m 4 in subjects allergic to birch pollen with soy allergy and to assess the risk for subjects allergic to birch pollen to acquire soy allergy., Methods: Twenty-two patients allergic to birch pollen with soy allergy confirmed by means of positive double-blind, placebo-controlled food challenge results (n = 16) or a convincing history (n = 6) were investigated for IgE reactivity to birch pollen and soy allergens by using the Pharmacia CAP system and immunoblot analysis. Cross-reactivity was assessed by means of enzyme allergosorbent test inhibition. Ninety-four patients with birch pollen allergy were interviewed to assess soy tolerance and screened for IgE reactivity to Gly m 4 by means of immunoblotting. The Gly m 4 content in soy foods and soybean varieties was investigated by means of quantitative evaluation of immunoblots., Results: During double-blind, placebo-controlled food challenge, 10 patients experienced symptoms localized to the oral cavity, and 6 patients had a more severe reaction. CAP analysis revealed Gly m 4-specific IgE in 96% (21/22) of the patients. All patients had Bet v 1-specific IgE antibodies, and 23% (5/22) had positive Bet v 2 results. In IgE immunoblotting 25% (6/22) of the patients recognized soy profilin (Gly m 3), and 64% (14/22) recognized other soy proteins. IgE binding to soy was at least 80% inhibited by birch pollen and 60% inhibited by rGly m 4 in 9 of 11 sera tested. Seventy-one percent (67/94) of highly Bet v 1-sensitized patients with birch pollen allergy were sensitized to Gly m 4, and 9 (9.6%) of those patients reported soy allergy. The Gly m 4 content in soy products ranged between 0 and 70 ppm (milligrams per kilogram)., Conclusions: Our results confirm that soybean is another birch pollen-related allergenic food. Gly m 4 is the major soy allergen for patients allergic to birch pollen with soy allergy. The content of Gly m 4 in soy food products strongly depends on the degree of food processing.

Background: Quorn is the brand name for a line of foods made with so-called "mycoprotein," which springs from the mold Fusarium venenatum. Since the introduction on the food market, there have been complaints from consumers reporting adverse gastrointestinal reactions after ingestion of mycoprotein. To date, it is not clear whether the reported symptoms are IgE-mediated., Objective: The aim of the study was to describe for the first time a case history of an asthmatic patient with severe hypersensitivity reactions to ingested mycoprotein and to identify and characterize the potential allergen that might be responsible for this., Methods: The sensitization pattern of the asthmatic subject was characterized, and food allergy to mycoprotein was assessed by double-blinded placebo-controlled food challenge. Afterward, specific IgE antibodies of the serum of this patient were used to screen a Fusarium culmorum cDNA expression library. The coding sequence of one enriched cDNA-clone was expressed in Escherichia coli to produce a recombinant protein that was further purified and immunologically characterized., Results: The patient showed high sensitization to many known aeroallergens but apart from Quorn not to any other tested food samples. The deduced amino acid sequence of the enriched cDNA-clone (Fus c 1) showed large identity to the 60S acidic ribosomal protein P2 which is highly conserved among several species and also described as minor allergen in other mold species. The frequency of IgE reactivity of sera from F culmorum -sensitized subjects to rFus c 1 was approximately 35%. By enzyme allergosorbent test inhibition, we found 65% inhibition of mycoprotein IgE reactivity by rFus c 1. On the opposite we found reduced IgE reactivity of rFus c 1 of 68% by using mycoprotein as inhibitor., Conclusions: Sensitization to mold allergens by the respiratory tract and subsequent oral ingestion of cross-reactive proteins may lead to severe food-allergic reactions. Thus, the 60S acidic ribosomal protein P2 of F venenatum probably is the reason for the described severe hypersensitivity reactions of the patient to Quorn-mycoprotein because of its potential cross-reactivity to the F culmorum allergen Fus c 1.

Background: In pollen-related food allergy, extracts for skin prick tests (SPTs) are often not standardized, and the test reliability is affected by false-negative reactions., Objective: We sought to evaluate a panel of recombinant allergens (RAs) derived from one allergenic food for use in component-resolved in vivo diagnosis, taking cherry as a model food., Methods: Seventy-nine subjects were included in the study: 24 Swiss patients (group 1) with a positive double-blind placebo-controlled food challenge result to cherries, 23 patients with birch pollen allergy but without cherry allergy (group 2), 23 nonatopic subjects (group 3), and 9 Spanish patients with a history of a cherry allergy (group 4). SPTs were performed in duplicate by using recombinant cherry allergens (Bet v 1-related allergen: recombinant (r) Pru av 1; profilin: rPru av 4; and lipid transfer protein: rPru av 3) in concentrations of 10, 50, and 100 microg/mL. Furthermore, IgE reactivity to rPru av 1, rPru av 4, and rPru av 3 was assessed by means of immunoblot analysis., Results: SPT responses with rPru av 1, rPru av 4, and rPru av 3 were positive in 92%, 17%, and 4% of the patients in group 1; in 74%, 30%, and 0% of the patients in group 2; in 0%, 22%, and 89% of the patients in group 4; and negative for all nonatopic subjects (group 3). Thus the sensitivity of a positive SPT response to at least one of the 3 RAs was 96%. The specificities, negative predictive values, and positive predictive values with the 3 RAs were 100%, 96%, and 100% if calculated in relation to the nonatopic control group but 17%, 79%, and 60% when calculated in relation to the control group with birch pollen allergy. The correlation between SPT and immunoblotting results was excellent. Sensitization to rPru av 3 was associated with more severe symptoms than sensitization to rPru av 1., Conclusions: SPTs with RAs proved to be highly sensitive for diagnosis of cherry allergy. Component-resolved in vivo diagnosis with standardized amounts of stable RAs allows us to determine sensitization patterns directly, to correlate them with severity of clinical symptoms, and to analyze geographic differences.

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 SDS-PAGE 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.