Cross-reactivity of peanut allergens.
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ABSTRACT:
SUBMITTER: Bublin M
PROVIDER: S-EPMC3962743 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Peanut allergens have the potential to negatively impact on the health and quality of life of millions of consumers worldwide. The seeds of the peanut plant Arachis hypogaea contain an array of allergens that are able to induce the production of specific IgE antibodies in predisposed individuals. A lot of effort has been focused on obtaining the sequences and structures of these allergens due to the high health risk they represent. At present, 16 proteins present in peanuts are officially recognized as allergens. Research has also focused on their in-depth immunological characterization as well as on the design of modified hypoallergenic derivatives for potential use in clinical studies and the formulation of strategies for immunotherapy. Detailed research protocols are available for the purification of natural allergens as well as their recombinant production in bacterial, yeast, insect, and algal cells. Purified allergen molecules are now routinely used in diagnostic multiplex protein arrays for the detection of the presence of allergen-specific IgE. This review gives an overview on the wealth of knowledge that is available on individual peanut allergens.
| S-EPMC7060077 | biostudies-literature
Project description:BACKGROUND:Allergic sensitisation towards cashew nut often happens without a clear history of eating cashew nut. IgE cross-reactivity between cashew and pistachio nut is well described; however, the ability of cashew nut-specific IgE to cross-react to common tree nut species and other Anacardiaceae, like mango, pink peppercorn, or sumac is largely unknown. OBJECTIVES:Cashew nut allergic individuals may cross-react to foods that are phylogenetically related to cashew. We aimed to determine IgE cross-sensitisation and cross-reactivity profiles in cashew nut-sensitised subjects, towards botanically related proteins of other Anacardiaceae family members and related tree nut species. METHOD:Sera from children with a suspected cashew nut allergy (n = 56) were assessed for IgE sensitisation to common tree nuts, mango, pink peppercorn, and sumac using dot blot technique. Allergen cross-reactivity patterns between Anacardiaceae species were subsequently examined by SDS-PAGE and immunoblot inhibition, and IgE-reactive allergens were identified by LC-MS/MS. RESULTS:From the 56 subjects analysed, 36 were positive on dot blot for cashew nut (63%). Of these, 50% were mono-sensitised to cashew nuts, 19% were co-sensitised to Anacardiaceae species, and 31% were co-sensitised to tree nuts. Subjects co-sensitised to Anacardiaceae species displayed a different allergen recognition pattern than subjects sensitised to common tree nuts. In pink peppercorn, putative albumin- and legumin-type seed storage proteins were found to cross-react with serum of cashew nut-sensitised subjects in vitro. In addition, a putative luminal binding protein was identified, which, among others, may be involved in cross-reactivity between several Anacardiaceae species. CONCLUSIONS:Results demonstrate the in vitro presence of IgE cross-sensitisation in children towards multiple Anacardiaceae species. In this study, putative novel allergens were identified in cashew, pistachio, and pink peppercorn, which may pose factors that underlie the observed cross-sensitivity to these species. The clinical relevance of this widespread cross-sensitisation is unknown.
| S-EPMC6381869 | biostudies-literature
Project description:Allergenic proteins from very different environmental sources have similar sequences and structures. This fact may account for multiple allergen syndromes, whereby a myriad of diverse plants and foods may induce a similar IgE-based reaction in certain patients. Identifying the common triggering protein in these sources, in silico, can aid designing individualized therapy for allergen sufferers. This article provides an overview of databases on allergenic proteins, and ways to identify common proteins that may be the cause of multiple allergy syndromes. The major emphasis is on the relational Structural Database of Allergenic Proteins (SDAP []), which includes cross-referenced data on the sequence, structure, and IgE epitopes of over 800 allergenic proteins, coupled with specially developed bioinformatics tools to group all allergens and identify discrete areas that may account for cross-reactivity. SDAP is freely available on the Web to clinicians and patients.
| S-EPMC1941676 | biostudies-literature
Project description:BackgroundPollen released by allergenic members of the botanically unrelated families of Asteraceae and Cupressaceae represent potent elicitors of respiratory allergies in regions where these plants are present. As main allergen sources the Asteraceae species ragweed and mugwort, as well as the Cupressaceae species, cypress, mountain cedar, and Japanese cedar have been identified. The major allergens of all species belong to the pectate lyase enzyme family. Thus, we thought to investigate cross-reactivity pattern as well as sensitization capacities of pectate lyase pollen allergens in cohorts from distinct geographic regions.MethodsThe clinically relevant pectate lyase pollen allergens Amb a 1, Art v 6, Cup a 1, Jun a 1, and Cry j 1 were purified from aqueous pollen extracts, and patients' sensitization pattern of cohorts from Austria, Canada, Italy, and Japan were determined by IgE ELISA and cross-inhibition experiments. Moreover, we performed microarray experiments and established a mouse model of sensitization.ResultsIn ELISA and ELISA inhibition experiments specific sensitization pattern were discovered for each geographic region, which reflected the natural allergen exposure of the patients. We found significant cross-reactivity within Asteraceae and Cupressaceae pectate lyase pollen allergens, which was however limited between the orders. Animal experiments showed that immunization with Asteraceae allergens mainly induced antibodies reactive within the order, the same was observed for the Cupressaceae allergens. Cross-reactivity between orders was minimal. Moreover, Amb a 1, Art v 6, and Cry j 1 showed in general higher immunogenicity.ConclusionWe could cluster pectate lyase allergens in four categories, Amb a 1, Art v 6, Cup a 1/Jun a 1, and Cry j 1, respectively, at which each category has the potential to sensitize predisposed individuals. The sensitization pattern of different cohorts correlated with pollen exposure, which should be considered for future allergy diagnosis and therapy.
| S-EPMC4433284 | biostudies-literature
Project description:BackgroundPatients with peanut allergy have highly stable pathologic antibody repertoires to the immunodominant B-cell epitopes of the major peanut allergens Ara h 1 to 3.ObjectiveWe used a peptide microarray technique to analyze the effect of treatment with peanut oral immunotherapy (OIT) on such repertoires.MethodsMeasurements of total peanut-specific IgE (psIgE) and peanut-specific IgG(4) (psIgG(4)) were made with CAP-FEIA. We analyzed sera from 22 patients with OIT and 6 control subjects and measured serum specific IgE and IgG(4) binding to epitopes of Ara h 1 to 3 using a high-throughput peptide microarray technique. Antibody affinity was measured by using a competitive peptide microarray, as previously described.ResultsAt baseline, psIgE and psIgG(4) diversity was similar between patients and control subjects, and there was broad variation in epitope recognition. After a median of 41 months of OIT, polyclonal psIgG(4) levels increased from a median of 0.3 μg/mL (interquartile range [25% to 75%], 0.1-0.43 μg/mL) at baseline to 10.5 μg/mL (interquartile range [25% to 75%], 3.95-45.48 μg/mL; P < .0001) and included de novo specificities. psIgE levels were reduced from a median baseline of 85.45 kU(A)/L (23.05-101.0 kU(A)/L) to 7.75 kU(A)/L (2.58-30.55 kU(A)/L, P < .0001). Affinity was unaffected. Although the psIgE repertoire contracted in most OIT-treated patients, several subjects generated new IgE specificities, even as the total psIgE level decreased. Global epitope-specific shifts from IgE to IgG(4) binding occurred, including at an informative epitope of Ara h 2.ConclusionOIT differentially alters Ara h 1 to 3 binding patterns. These changes are variable between patients, are not observed in control subjects, and include a progressive polyclonal increase in IgG(4) levels, with concurrent reduction in IgE amount and diversity.
| S-EPMC3529994 | biostudies-literature
Project description:Cross-reactivity between peanuts and tree nuts implies that similar immunoglobulin E (IgE) epitopes are present in their proteins.To determine whether walnut sequences similar to known peanut IgE-binding sequences, according to the property distance (PD) scale implemented in the Structural Database of Allergenic Proteins, react with IgE from sera of patients with allergy to walnut and/or peanut.? Patient sera were characterized by western blotting for IgE binding to nut protein extracts and to peptides from walnut and peanut allergens, similar to known peanut epitopes as defined by low PD values, synthesized on membranes. Competitive enzyme-linked immunosorbent assay (ELISA) was used to show that peanut and predicted walnut epitope sequences compete with purified Ara h 2 for binding to IgE in serum from a cross-reactive patient.Sequences from the vicilin walnut allergen Jug r 2, which had low PD values to epitopes of the peanut allergen Ara h 2, a 2S albumin, bound to IgE in sera from five patients who reacted to either walnut or peanut or both. A walnut epitope recognized by sera from six patients mapped to a surface-exposed region on a model of the N-terminal pro-region of Jug r 2. This predicted walnut epitope competed for IgE binding to Ara h 2 in serum as well as the known IgE epitope from Ara h 2.Sequences with low PD value (< 8.5) to known IgE epitopes could contribute to cross-reactivity between allergens. This further validates the PD scoring method for predicting cross-reactive epitopes in allergens.
| S-EPMC3203311 | biostudies-literature
Project description:BackgroundGrasses and olive trees are the most common sources of allergenic pollen worldwide. Although they share some allergens, there are few studies analyzing the in vitro cross-reactivity between them. The aim was to define the cross-reactivity between Olea europaea and Phleum pratense using well-characterized sera of allergic children from Madrid, Spain.Methods66 patients (mean age 10.32+/-4.07 years) were included in the study. All suffered from rhinoconjuntivitis and/or asthma and had a positive skin test and/or specific IgE determination to olive and grass pollen. Serum sIgE to individual allergens was conducted and sIgE against different grass species and olive was also determined by ELISA. Inhibition assays were performed using two serum sources, containing, or not, sIgE to minor allergens. Mass spectrometry analysis was performed in both extracts.Results59/66 (89.39%) children had a positive sIgE determination by ELISA to grasses and 57/66 (86.36%) to olive pollen. There was no significant correlation between sIgE levels to grass and olive. Inhibition assays demonstrated no cross-reactivity between P. pratense and olive pollen when using the pool containing mainly sIgE to major allergens, whereas minimal to moderate cross-reactivity was detected when the serum contained high sIgE titers to minor allergens. Proteomic analyses revealed the presence of 42 common proteins in grasses and olive pollens.ConclusionNo in vitro cross-reactivity was observed when sIgE was mainly directed to major allergens. In our population, sensitization to olive and grasses is not due to cross-reactivity. The contribution of the major allergens seems to be determinant.
| S-EPMC4045862 | biostudies-literature
Project description:BackgroundMost children with detectable peanut-specific IgE (P-sIgE) are not allergic to peanut. We addressed 2 non-mutually exclusive hypotheses for the discrepancy between allergy and sensitization: (1) differences in P-sIgE levels between children with peanut allergy (PA) and peanut-sensitized but tolerant (PS) children and (2) the presence of an IgE inhibitor, such as peanut-specific IgG4 (P-sIgG4), in PS patients.MethodsTwo hundred twenty-eight children (108 patients with PA, 77 PS patients, and 43 nonsensitized nonallergic subjects) were studied. Levels of specific IgE and IgG4 to peanut and its components were determined. IgE-stripped basophils or a mast cell line were used in passive sensitization activation and inhibition assays. Plasma of PS subjects and patients submitted to peanut oral immunotherapy (POIT) were depleted of IgG4 and retested in inhibition assays.ResultsBasophils and mast cells sensitized with plasma from patients with PA but not PS patients showed dose-dependent activation in response to peanut. Levels of sIgE to peanut and its components could only partially explain differences in clinical reactivity between patients with PA and PS patients. P-sIgG4 levels (P = .023) and P-sIgG4/P-sIgE (P < .001), Ara h 1-sIgG4/Ara h 1-sIgE (P = .050), Ara h 2-sIgG4/Ara h 2-sIgE (P = .004), and Ara h 3-sIgG4/Ara h 3-sIgE (P = .016) ratios were greater in PS children compared with those in children with PA. Peanut-induced activation was inhibited in the presence of plasma from PS children with detectable P-sIgG4 levels and POIT but not from nonsensitized nonallergic children. Depletion of IgG4 from plasma of children with PS (and POIT) sensitized to Ara h 1 to Ara h 3 partially restored peanut-induced mast cell activation (P = .007).ConclusionsDifferences in sIgE levels and allergen specificity could not justify the clinical phenotype in all children with PA and PS children. Blocking IgG4 antibodies provide an additional explanation for the absence of clinical reactivity in PS patients sensitized to major peanut allergens.
| S-EPMC4418748 | biostudies-literature
Project description:BackgroundNovel protein sources can represent a risk for allergic consumers. The aim of this study was to evaluate the allergenicity of cowpea (Vigna unguiculata), an increasingly consumed legume and potential new industrial food ingredient which may put legume-allergic patients at risk.MethodsChildren with allergy to legumes associated to peanut (LP group: n = 13) or without peanut allergy (L group: n = 14) were recruited and sensitization to several legumes including cowpea was assessed by prick tests and detection of specific IgE (sIgE). Cowpea protein extract was analyzed by SDS-PAGE and immunoblotting, IgE-reactive spots were subjected to mass spectrometry. IgE-cross-reactivity between cowpea, pea, and peanut was determined using ELISA inhibition assays. Basophil activation tests were performed to evaluate sensitivity and reactivity of patient basophils toward legumes.ResultsPrick tests and sIgE levels to cowpea were positive in 8/14 and 4/13 patients of the L group and in 9/13 and 10/13 patients of the LP group, respectively. Four major IgE-binding proteins were identified as vicilins and seed albumin. Cowpea extract and its vicilin fraction strongly inhibited IgE-binding to pea and peanut extract. Peanut, lentil, and pea were the strongest activators of basophils, followed by cowpea, soybean, mung bean, and lupin.ConclusionA majority of patients with legume allergy were sensitized to cowpea proteins. Four novel allergens were identified in cowpea, among which storage proteins were playing an important role in IgE-cross-reactivity, exposing legume-allergic patients to the risk of clinical cross-reactivity to cowpea and thus adding cowpea to the group of nonpriority legumes that are not subjected to allergen labeling such as chickpea, pea, and lentil.
| S-EPMC10108199 | biostudies-literature
Project description:Vicilin-buried peptides (VBPs) from edible plants are derived from the N-terminal leader sequences (LSs) of seed storage proteins. VBPs are defined by a common α-hairpin fold mediated by conserved CxxxCx(10-14)CxxxC motifs. Here, peanut and walnut VBPs were characterized as potential mediators of both peanut/walnut allergenicity and cross-reactivity despite their low (∼17%) sequence identity. The structures of one peanut (AH1.1) and 3 walnut (JR2.1, JR2.2, JR2.3) VBPs were solved using solution NMR, revealing similar α-hairpin structures stabilized by disulfide bonds with high levels of surface similarity. Peptide microarrays identified several peptide sequences primarily on AH1.1 and JR2.1, which were recognized by peanut-, walnut-, and dual-allergic patient IgE, establishing these peanut and walnut VBPs as potential mediators of allergenicity and cross-reactivity. JR2.2 and JR2.3 displayed extreme resilience against endosomal digestion, potentially hindering epitope generation and likely contributing to their reduced allergic potential.
| S-EPMC8959100 | biostudies-literature