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Scope: Edible insects contain allergens with potential cross-reactivity to other invertebrates. Here, this study examines IgE-reactive proteins in a house cricket snack (Acheta domesticus) leading to an allergic reaction in a 27-year old man followed by a similar reaction days later after eating shrimps., Methods and Results: Prick to prick tests verify the IgE-mediated allergy to crickets and skin prick testing confirms a type I sensitization to house dust mite without any clinical relevance for the patient, and to shrimp extracts, but is negative for several other foods. Serological testing reveals a sensitization to shrimps, shrimp tropomyosin, and house dust mite tropomyosin. IgE-immunodetection shows that the cricket allergic patient is sensitized to two proteins of 45 and >97 kDa using aqueous control cricket extract, but to only one protein at around 45 kDa when using the causative, seasoned insect snack extract. Mass spectrometry data and IgE-inhibition experiments clearly identify this protein belonging to the tropomyosin allergen family., Conclusion: This case report suggests that cricket tropomyosin may be an elicitor of allergic reactions even in previously not allergic patients, although it cannot be excluded the patient reacted additionally to other ingredients of the snack., (© 2024 The Authors. Molecular Nutrition & Food Research published by Wiley‐VCH GmbH.)

Scope: Carrot (Daucus carota) allergy is caused by the major carrot allergen Dau c 1, which is a mixture of several isoallergens and variants with sequence identities of >67% or >90%, respectively. However, little is known about the qualitative and quantitative composition of natural Dau c 1., Methods and Results: Mass spectrometry of isolated natural Dau c 1 reveals the existence of several yet unknown Dau c 1-like proteins. The study expresses four Dau c 1-like proteins in Escherichia coli. Two of the purified proteins, designated Dau c 1.0501 and 1.0601, exhibit sequence identities to Dau c 1.0101 and 1.0401 between 54% and 87%. They possess allergenic potential and are accepted as new isoallergens. One protein, designated as Dau c 1-like is >50% identical with the new isoallergens but exhibits no allergenicity. Sequence and structural comparisons of this protein with the known Dau c 1 isoallergens offer relevant clues about putative structural IgE epitopes., Conclusion: Identification of new isoallergens and the identification of IgE epitopes may contribute to a more refined component resolved diagnosis and may lay ground for further epitope mapping and personalized targeted treatment approaches of carrot allergy in preclinical and clinical studies., (© 2022 The Authors. Molecular Nutrition & Food Research published by Wiley-VCH GmbH.)

Scope: Around 25% of food allergic persons in Central Europe suffer from carrot allergy caused by the major carrot allergen Dau c 1. Three different isoallergens, Dau c 1.01, Dau c 1.02 and Dau c 1.03 are identified. However, information about the qualitative and quantitative composition of natural (n)Dau c 1 is scarce., Methods and Results: The new carrot allergen Dau c 1.0401 is identified on the mRNA and protein level by RT-PCR and mass spectrometry. It displays only around 60% sequence identity to the other known Dau c 1 isoallergens. NMR and CD-spectra are typical for a well-folded protein containing both α-helices and β-strands. It showed a poor refolding capacity after incubation at 95 °C. IgE-binding is impaired in immunoblots, whereas in inhibition assays IgE binding to soluble Dau c 1.0401 is detected and it clearly provoked a response in mediator release assays., Conclusion: Dau c 1.0401 is a new isoallergen which contributes to the allergenicity of carrots. The absence of immunoreactivity in immobilized assays indicates that IgE binding is impaired when the protein is blotted on a solid phase. Altogether, the results point out that its allergenicity can be reduced upon carrot processing., (© 2021 The Authors. Molecular Nutrition & Food Research published by Wiley-VCH GmbH.)

Scope: Chickpea (Cicer arietinum) allergy has frequently been reported particularly in Spain and India. Nevertheless, chickpea allergens are poorly characterized. The authors aim to identify and characterize potential allergens from chickpea., Methods and Results: Candidate proteins are selected by an in silico approach or immunoglobuline E (IgE)-testing. Potential allergens are prepared as recombinant or natural proteins and characterized for structural integrity by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), circular dichroism (CD)-spectroscopy, and mass spectrometry (MS) analysis. IgE-sensitization pattern of Spanish chickpea allergic and German peanut and birch pollen sensitized patients are investigated using chickpea extracts and purified proteins. Chickpea allergic patients show individual and heterogeneous IgE-sensitization profiles with extracts from raw and boiled chickpeas. Chickpea proteins pathogenesis related protein family 10 (PR-10), a late embryogenesis abundant protein (LEA/DC-8), and a vicilin-containing fraction, but not 2S albumin, shows IgE reactivity with sera from chickpea, birch pollen, and peanut sensitized patients. Remarkably, allergenic vicilin, DC-8, and PR-10 are detected in the extract of boiled chickpeas., Conclusion: Several IgE-reactive chickpea allergens are identified. For the first time a yet not classified DC-8 protein is characterized as minor allergen (Cic a 1). Finally, the data suggest a potential risk for peanut allergic patients by IgE cross-reactivity with homologous chickpea proteins., (© 2020 Wiley-VCH GmbH.)

Scope: The major carrot allergen Dau c 1 belongs to the group of pathogenesis related class 10 (PR-10) proteins and is homologous to the birch pollen allergen Bet v 1. In contrast to most other PR-10 allergens, Dau c 1 can elicit Bet v 1 independent sensitization. Although Dau c 1 is considered heat labile, allergic reactions against cooked carrots are possible., Methods and Results: The pH and temperature stability as well as the allergenic potential before and after treatment of purified natural (n) Dau c 1 and different recombinant (r) isoallergens is investigated: rDau c 1.0104, rDau c 1.0105, rDau c 1.0201, rDau c 1.0301. All proteins except rDau c 1.0201 are able to refold at physiological pH. pH conditions around the pI (4.4-5.5) or the presence of the carrot matrix reduce the refolding capacity. Below the pI, most isoallergens are heat resistant and still able to cause mediator release, indicating allergenicity. Moreover, cooked carrot extract is still able to provoke mediator release due to remaining soluble Dau c 1., Conclusion: Patients allergic to carrots should avoid processed carrot containing foodstuff because heating or pH treatment do not completely abolish the allergenicity of Dau c 1., (© 2020 The Authors. Published by Wiley-VCH GmbH.)

Scope: English walnut (Juglans regia) belongs to the most important allergenic tree nuts. Co-sensitization with birch (Betula verrucosa) pollen has been reported. We aimed to identify a walnut allergen homologous to the major birch pollen allergen Bet v 1., Methods and Results: A cDNA encoding a Bet v 1-homologous allergen (Jug r 5) in walnut kernels was cloned by RT-PCR. Jug r 5 was expressed in Escherichia coli, purified by column chromatography and characterized by circular dichroism spectroscopy. Specific IgE levels to walnut, Bet v 1, and Jug r 5 in birch pollen allergics (n = 16) with concomitant walnut allergy were measured by ImmunoCAP: 44% of the patients were tested positive to walnut while 94% were reactive to Jug r 5, and 100% to Bet v 1. Jug r 5 and Bet v 1 allergens showed bidirectional IgE cross-reactivity by competitive ELISA and were capable of inducing histamine release from effector cells. Immunoblot competition experiments demonstrated the presence of IgE-reactive Jug r 5 in walnut extract, but at low levels., Conclusion: A Bet v 1-like allergen was identified in walnut. Diagnostic use of Jug r 5 will compensate for the low sensitivity of walnut extract for patients with birch pollen associated walnut allergy., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Scope: The aim was to investigate the potential contribution of a major birch pollen Bet v 1-homologous allergen to birch pollen-associated tomato fruit allergy., Methods and Results: Two isoforms of a Bet v 1-homologous protein (designated Sola l 4) from tomato fruit were identified by cDNA-cloning and produced as recombinant proteins. Allergen-specific IgE levels to tomato, birch pollen, Bet v 1, and Sola l 4 were determined in birch pollen allergic patients with allergy or tolerance to tomato. Sola l 4 was recognized in 76% of birch/tomato allergic patients, while tomato- and Bet v 1-specific IgE was detectable in 64% and 81% of sera. Almost all patients sensitized to Bet v 1 reacted with Sola l 4. Both Sola l 4 isoforms displayed allergenic potency and IgE-cross-reactivity with Bet v 1 as investigated by competitive ELISA and in vitro mediator release assay. Nevertheless, the reactivity pattern of patients' sera was diverse., Conclusion: Sola l 4, a novel pathogenesis related-10 protein, qualifies as major allergen in tomato fruits. Data suggest Sola l 4 as class II allergen. IgE-testing using Sola l 4 showed low clinical specificity, but high sensitivity in tomato allergic patients and will further improve component-resolved allergy diagnosis., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Scope: Four Bet v 1 homologous food allergens from celeriac (rApi g 1), apple (rMal d 1), peach (rPru p 1) and hazelnut (rCor a 1), were used to probe the structural responsiveness of the Bet v 1 scaffold to gastric digestion conditions and its impact on allergenicity., Methods and Results: Low pH induced conformational changes of all homologues, which was reduced at physiological ionic strength for all except rPru p 1 as observed by circular dichroism (CD)-spectroscopy. The homologues were rapidly digested by pepsin, losing their IgE binding activity, although the kinetics and patterns of digestion varied subtly between homologues, rApi g 1 being the most stable. We have demonstrated for the first time that gastric phosphatidyl-choline (PC) induced conformational changes in all homologues but only rMal d 1 penetrated the PC vesicles as detected by fluorescence polarization, slowing its digestion and retaining more of its allergenic activity. PC enhanced basophil activation of all digested allergens except rApi g 1., Conclusion: The Bet v 1 scaffold is generally susceptible to low pH and pepsinolysis and interacts with PC vesicles, properties which can explain effects of the gastric environment on their allergenicity. These data show the importance of including surfactants in model digestion systems., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)