Cross-reactivity Of IgE Antibodies Research Articles

B-060 Prevalence of CCD and profilins antibodies in a seasonal allergy study

Abstract Background Allergen sources are complex and heterogeneous mixtures of proteins, which may contain from innocuous IgE-binding structures such as CCDs (cross-reactive carbohydrate determinants), which are not associated with symptoms, to a panallergen such as profilin, which is associated with multiple sensitizations to pollen and pollen-food-latex syndromes. CCDs are present in many plant and animal allergens and cause strong cross-reactivity due to the high similarity of their structure. They complicate the interpretation of positive in vitro diagnostic results because they do not associate symptomatology and, thats why, the determination of specific IgE antibodies against CCDs can provide useful information when positive IgE results are not consistent with the clinical picture. Profilins are ubiquitous proteins present in all eukaryotic cells and identified as allergens in pollen, latex and plant foods. The highly conserved structure explains the cross-reactivity of IgE antibodies against plant profilins and their designation as panallergens. As a panallergen, profilin is associated with multiple pollen sensitization and pollen-food-latex syndromes that the allergist must be aware of for accurate diagnosis and successful treatment of allergic diseases. We intend to evaluate the prevalence of these two markers with a new diagnostic tool, since profilins and CCDs are the substances most likely to cause in vitro cross-reactivity. Methods In our study 8,242 adults who presented rhinoconjunctivitis and visited their primary care center were included. The samples were analyzed in serum samples which were routinely processed in our laboratory with the EUROLINE Mediterranean Inhalation 2 (IgE) assay from Euroimmun® from February to July 2023, according to the manufacturer’s protocols. Patients with specific IgE levels ≥ 0.35 kU/L were identified as sensitized to allergen. Results A total of 8,242 patients were enrolled in this study, 5,173 women and 3,069 men, ranging in age from 15 to 65 years. Of these, 279 patients (3.39%) had antibodies against CCD, 570 (6.92%) antibodies against profilins and 183 (2.22%) had both. A higher prevalence of these antibodies was observed in men (CCD, n = 168, 5.47%; Profilins, n = 308, 10.04%) than in women (CCD, n = 111, 2.15%; Profilins, n = 262, 5.06%). Both markers were more frequently found in the presence of specific IgE antibodies to grass and weed pollens. Conclusions The possibility of detecting the presence of IgE antibodies against CCD and panallergenic profilins is useful to detect cross-reactivity in vitro, which could explain the differences found between laboratory results and patients' symptoms, helping the allergist to make a diagnosis with greater certainty and accuracy.

Allergenicity and structural properties of new Cor a 1 isoallergens from hazel identified in different plant tissues

The hazel allergen Cor a 1 is a PR-10 protein, closely related to the major birch pollen allergen Bet v 1. Hazel allergies are caused by cross-reactive IgE antibodies originally directed against Bet v 1. Despite the importance of PR-10 proteins in allergy development, their function and localization in the plant remain largely elusive. Therefore, the presence of Cor a 1 mRNA and proteins was investigated in different tissues, i.e., the female flower, immature and mature nuts, catkins, and pollen. Four yet unknown Cor a 1 isoallergens, i.e., Cor a 1.0501–1.0801, and one new Cor a 1.03 variant were discovered and characterized. Depending on the isoallergen, the occurrence and level of mRNA expression varied in different tissues, suggesting different functions. Interestingly, Cor a 1.04 previously thought to be only present in nuts, was also detected in catkins and pollen. The corresponding Cor a 1 genes were expressed in Escherichia coli. The purified proteins were analysed by CD and NMR spectroscopy. Immunoblots and ELISAs to determine their allergenic potential showed that the new proteins reacted positively with sera from patients allergic to birch, hazel and elder pollen and were recognized as novel isoallergens/variants by the WHO/IUIS Allergen Nomenclature Sub-Committee.

Evolution Toward Chip-Based Arrays in the Laboratory Diagnosis of Human Allergic Disease.

Multiplex-based specific IgE antibody assays have emerged into the clinical immunology laboratory through the combined use of pure, recombinant allergenic molecules and new methods to simultaneously and accurately analyze specific IgE antibodies to hundreds of allergens. This review traces the historical development and examines outstanding questions related to the strengths and limitations of these new molecular allergen multipex technologies for the assessment of human allergic sensitization. Multiplexed technologies are poised to provide the most cost-effective and comprehensive evaluation of patients with suspected allergy as compared with the commonly used singleplex autoanalyzers. How analytically sensitive and quantitative are the multiplex technologies, down to 0.1 kUA/L? Because each allergen is viewed as a unique assay, how will analytical and clinical performance be documented at the manufacturing and clinical laboratory levels to guarantee reproducibility and obtain government regulatory clearance? Will interference by naturally occurring allergen-specific IgG compromise analytical performance? Successful resolution of these and other questions covered in this review will position multiplex technologies to become the single most-effective means of screening patients for allergic sensitization, assessing IgE antibody cross-reactivity, and planning therapy directed at the patient with allergy.

Cross-Reactive Shellfish-specific Monoclonal IgE Antibodies Discovered from Highly Allergic Individuals

The prevalence of shellfish allergy[JG1] [DC2] is 1.5-2.5% in the United States and is even higher in Southeast Asia. Shellfish antigens can elicit potent IgE responses [DC3] in individuals with severe allergies; however, the difficulty of discovering human monoclonal IgE antibodies has slowed progress in understanding the origins of allergen cross-reactivity at the molecular level.

An in-silico approach of allergenicity reduction in PR10 and Profilin families of pan allergens using allergen-IgE docking analysis

The pan-allergen includes proteins families, which are involved in general essential processes and, thus, generally distributed throughout nature. Plant pan-allergens are in charge of many IgE cross-reactions against plant food and pollen allergen sources. Pan-allergens that have been analyzed in this study are profilin and PR10 families. profilins are present in the cytoplasm of the cell and PR10 is important for controlling the growth of actin microfilaments. The cross-reactivity of IgE antibodies is a key factor in allergy occurrence. In this study, the 3-D structures of Amb a 8, Ara h 5, and Cyn d 12 of profilin family, and that of Bet v 1, Pru av 1, and Gly m 4 of PR10 family were obtained, mutated Amb a 8 (N52→S, K56→R), Ara h 5 (A54→L, A60→L), Cyn d 12 (H10→R, H19→R), Bet v 1 (N43→S, N47→S), Pru av 1 (N142→S, K152→R), Gly m 4 (K64→R, K69→R), and docked with IgE. Our results indicated that the binding energy of mutated structures to IgE decreased. This variation in the amino acid sequence and protein structure could lead to a reduction in their binding energy to IgE in the human body, resulting in a reduction in the release of histamine, which ultimately diminishes the allergy symptoms and sensitivity to the recombinant protein.

The Structural Flexibility of PR-10 Food Allergens.

PR-10 proteins constitute a major cause of food allergic reactions. Birch-pollen-related food allergies are triggered by the immunologic cross-reactivity of IgE antibodies with structurally homologous PR-10 proteins that are present in birch pollen and various food sources. While the three-dimensional structures of PR-10 food allergens have been characterized in detail, only a few experimental studies have addressed the structural flexibility of these proteins. In this study, we analyze the millisecond-timescale structural flexibility of thirteen PR-10 proteins from prevalent plant food sources by NMR relaxation-dispersion spectroscopy, in a comparative manner. We show that all the allergens in this study have inherently flexible protein backbones in solution, yet the extent of the structural flexibility appears to be strikingly protein-specific (but not food-source-specific). Above-average flexibility is present in the two short helices, α1 and α2, which form a V-shaped support for the long C-terminal helix α3, and shape the internal ligand-binding cavity, which is characteristic for PR-10 proteins. An in-depth analysis of the NMR relaxation-dispersion data for the PR-10 allergen from peanut reveals the presence of at least two subglobal conformational transitions on the millisecond timescale, which may be related to the release of bound low-molecular-weight ligands from the internal cavity.

Structure and Zeatin Binding of the Peach Allergen Pru p 1.

Peach (Prunus persica) is among the fruits most frequently reported to cause food allergies. Allergic reactions commonly result from previous sensitization to the birch pollen allergen Bet v 1, followed by immunological cross-reactivity of IgE antibodies to structurally related proteins in peach. In this study, we present the three-dimensional NMR solution structure of the cross-reactive peach allergen Pru p 1 (isoform Pru p 1.0101). This 17.5 kDa protein adopts the canonical Bet v 1 fold, composed of a seven-stranded β-sheet and three α-helices enclosing an internal cavity. In Pru p 1, the inner surface of the cavity contains an array of hydroxyl-bearing amino acids surrounded by a hydrophobic patch, constituting a docking site for amphiphilic molecules. NMR-guided docking of the cytokinin molecule zeatin to the internal cavity of Pru p 1 provides a structure-based rationale for the effect that zeatin binding has on the protein’s RNase activity.

Inverse relation between structural flexibility and IgE reactivity of Cor a 1 hazelnut allergens

A major proportion of allergic reactions to hazelnuts (Corylus avellana) are caused by immunologic cross-reactivity of IgE antibodies to pathogenesis-related class 10 (PR-10) proteins. Intriguingly, the four known isoforms of the hazelnut PR-10 allergen Cor a 1, denoted as Cor a 1.0401–Cor a 1.0404, share sequence identities exceeding 97% but possess different immunologic properties. In this work we describe the NMR solution structures of these proteins and provide an in-depth study of their biophysical properties. Despite sharing highly similar three-dimensional structures, the four isoforms exhibit remarkable differences regarding structural flexibility, hydrogen bonding and thermal stability. Our experimental data reveal an inverse relation between structural flexibility and IgE-binding in ELISA experiments, with the most flexible isoform having the lowest IgE-binding potential, while the isoform with the most rigid backbone scaffold displays the highest immunologic reactivity. These results point towards a significant entropic contribution to the process of antibody binding.

Effect of structural stability on endolysosomal degradation and T-cell reactivity of major shrimp allergen tropomyosin.

BackgroundTropomyosins are highly conserved proteins, an attribute that forms the molecular basis for their IgE antibody cross‐reactivity. Despite sequence similarities, their allergenicity varies greatly between ingested and inhaled invertebrate sources. In this study, we investigated the relationship between the structural stability of different tropomyosins, their endolysosomal degradation patterns, and T‐cell reactivity.MethodsWe investigated the differences between four tropomyosins—the major shrimp allergen Pen m 1 and the minor allergens Der p 10 (dust mite), Bla g 7 (cockroach), and Ani s 3 (fish parasite)—in terms of IgE binding, structural stability, endolysosomal degradation and subsequent peptide generation, and T‐cell cross‐reactivity in a BALB/c murine model.ResultsTropomyosins displayed different melting temperatures, which did not correlate with amino acid sequence similarities. Endolysosomal degradation experiments demonstrated differential proteolytic digestion, as a function of thermal stability, generating different peptide repertoires. Pen m 1 (Tm 42°C) and Der p 10 (Tm 44°C) elicited similar patterns of endolysosomal degradation, but not Bla g 7 (Tm 63°C) or Ani s 3 (Tm 33°C). Pen m 1–specific T‐cell clones, with specificity for regions highly conserved in all four tropomyosins, proliferated weakly to Der p 10, but did not proliferate to Bla g 7 and Ani s 3, indicating lack of T‐cell epitope cross‐reactivity.ConclusionsTropomyosin T‐cell cross‐reactivity, unlike IgE cross‐reactivity, is dependent on structural stability rather than amino acid sequence similarity. These findings contribute to our understanding of cross‐sensitization among different invertebrates and design of suitable T‐cell peptide‐based immunotherapies for shrimp and related allergies.

Effect of Amino Acid Polymorphisms of House Dust Mite Der p 2 Variants on Allergic Sensitization.

PurposeThe sequence variations of the Der p 2 allergen of Dermatophagoides pteronyssinus diverge along 2 pathways with particular amino acid substitutions at positions 40,47,111, and 114. The environmental prevalence and IgE binding to Der p 2 variants differ among regions. To compare IgE binding to Der p 2 variants between sera from Bangkok, Thailand and Perth, Western Australia with different variants and to determine the variant-specificity of antibodies induced by vaccination with recombinant variants.MethodsThe structures of recombinant variants produced in yeast were compared by circular dichroism and 1-anilinonaphthalene 8-sulfonic acid staining of their lipid-binding cavity. Sera from subjects in Bangkok and Perth where different variants are found were compared by the affinity (IC50) of IgE cross-reactivity to different variants and by direct IgE binding. Mice were immunized with the variants Der p 2.0101 and Der p 2.0110, and their IgG binding to Der p 2.0103, 2.0104, and 2.0109 was measured.ResultsThe secondary structures of the recombinant variants resembled the natural allergen but with differences in ANS binding. The IC50 of Der p 2.0101 required 7-fold higher concentrations to inhibit IgE binding to the high-IgE-binding Der p 2.0104 than for homologous inhibition in sera from Bangkok where it is absent, while in sera from Perth that have both variants the IC50 was the same and low. Reciprocal results were obtained for Der p 2.0110 not found in Perth. Direct binding revealed that Der p 2.0104 was best for detecting IgE in both regions, followed by Der p 2.0101 with binding to other variants showing larger differences. Mouse anti-Der p 2.0101 antibodies had a high affinity of cross-reactivity but bound poorly to other variants.ConclusionsThe affinity of IgE antibody cross-reactivity, the direct IgE binding, and the specificities of antibodies induced by vaccination show that measures of allergic sensitization and therapeutic strategies could be optimized with knowledge of Der p 2 variants.

Allergen of the Month—White Bursage

Allergen of the Month—White Bursage

Enlarging the toolbox for allergen epitope definition with an allergen-type model protein.

BackgroundBirch pollen-allergic subjects produce polyclonal cross-reactive IgE antibodies that mediate pollen-associated food allergies. The major allergen Bet v 1 and its homologs in plant foods bind IgE in their native protein conformation. Information on location, number and clinical relevance of IgE epitopes is limited. We addressed the use of an allergen-related protein model to identify amino acids critical for IgE binding of PR-10 allergens.Method Norcoclaurine synthase (NCS) from meadow rue is structurally homologous to Bet v 1 but does not bind Bet v 1-reactive IgE. NCS was used as the template for epitope grafting. NCS variants were tested with sera from 70 birch pollen allergic subjects and with monoclonal antibody BV16 reported to compete with IgE binding to Bet v 1.ResultsWe generated an NCS variant (Δ29NCSN57/I58E/D60N/V63P/D68K) harboring an IgE epitope of Bet v 1. Bet v 1-type protein folding of the NCS variant was evaluated by 1H-15N-HSQC NMR spectroscopy. BV16 bound the NCS variant and 71% (50/70 sera) of our study population showed significant IgE binding. We observed IgE and BV16 cross-reactivity to the epitope presented by the NCS variant in a subgroup of Bet v 1-related allergens. Moreover BV16 blocked IgE binding to the NCS variant. Antibody cross-reactivity depended on a defined orientation of amino acids within the Bet v 1-type conformation.ConclusionOur system allows the evaluation of patient-specific epitope profiles and will facilitate both the identification of clinically relevant epitopes as biomarkers and the monitoring of therapeutic outcomes to improve diagnosis, prognosis, and therapy of allergies caused by PR-10 proteins.

LTP cross-reactivity - primary sensitization to mugwort pollen LTP Art v 3, facilitates subsequent sensitisation to peach LTP Pru p 3 in mice

Non-specific lipid transfer proteins (nsLTPs) are important pollen and food allergens in the Mediterranean area. Peach LTP Pru p 3 is considered as primary sensitizer inducing LTP cross-reactive IgE antibodies. Despite the evidence on the importance of Pru p 3, it is unclear whether reactivity to multiple LTPs is due to antibody cross-reactivity or to independent sensitization events. Aim of the study was (1) to compare antigenicity of LTPs from pollen and food, and (2) to investigate whether primary sensitization to LTPs promotes secondary sensitization to LTPs from unrelated sources. IgE sensitization to peach LTP was compared in different mouse strains (C3H/HeJ, BALB/c, CBA/J). IgE high responder mice (CBA/J) were used to compare the antigenicity and IgE cross-reactivity of LTPs from pollen (mugwort/Art v 3, plane tree/Pla a 3, ragweed/Amb a 6) and foods (peach/Pru p 3, cherry/Pru av 3, hazelnut/Cor a 8). To investigate whether an established Th2 immune response to LTPs facilitates a secondary immune response and cross-reactivity to unrelated LTPs, CBA/J mice were immunized with (1) Pru p 3 followed by Art v 3, (2) Art v 3 followed by Pru p 3, and (3) a mixture of Pru p 3 and Art v 3. Induction of Pru p 3 and Art v 3 specific IgE and IgG titers, and cross-reactivity between the two LTPs were determined by ELISA. CBA and C3H mice showed strong IgE-responses to Pru p 3, whereas BALB/c mice did not. Remarkably, a species-specific immune response lacking any IgE- and IgG-cross-reactivity was observed for all tested LTPs except for Pru p 3 and Pru av 3. Although LTPs show high structural similarity, Pru p 3 and Art v 3 displayed different antigenicity. In comparison to Art v 3, Pru p 3 showed much lower IgE-sensitizing capacity. In contrast, IgE response to Pru p 3 was promoted in mice previously sensitized to Art v 3, which was even the case upon concurrent administration of both LTPs. Neither sequential immunization nor immunization with the mixture induced IgE antibodies to unrelated LTPs, e.g. Cor a 8. In summary, the immune response to LTPs in mice varied strongly between strains. The LTPs studied, displayed different immunogenic properties and did not induce cross-reactive IgE antibodies. Primary sensitization to the pollen LTP Art v 3 conditioned the animals for subsequent sensitization to the food LTP Pru p 3. The extent to which the findings are applicable to the manifestation of clinical cross-reactivity to LTPs in humans needs to be investigated.

Differences in the intrinsic immunogenicity and allergenicity of B et v 1 and related food allergens revealed by site‐directed mutagenesis

BackgroundBirch pollen allergies are frequently associated with adverse reactions to various fruits, nuts, or vegetables, described as pollen–food syndrome (PFS) and caused by cross-reactive IgE antibodies primarily directed against Bet v 1. Specific immunotherapy (SIT) represents an effective treatment for inhalant allergies; however, successful birch pollen SIT does not correlate well with the amelioration of concomitant food allergies.MethodsAs vaccine candidates, apple Mal d 1 as well as hazelnut Cor a 1 derivatives were designed by in silico backbone analyses of the respective allergens. The proteins were produced by site-directed mutagenesis as fold variants of their parental allergens. Because Mal d 1 and Cor a 1 form cysteine-mediated aggregates, nonaggregative cysteine to serine mutants were also generated. The proteins were characterized physicochemically, immunologically, and in in vivo models with or without adjuvant.ResultsThe structurally modified proteins showed significantly decreased IgE binding capacity. Notably, both in vivo models revealed reduced immunogenicity of the hypoallergenic fold variants. When formulated with alum, the monomeric cysteine mutants induced a similar immune response as the aggregated parental allergens, which is in contrast with data published on Bet v 1.ConclusionThese findings lead to the suggestion that the Bet v 1 structure has unique intrinsic properties, which could account for its high allergenicity. Obviously, these characteristics are not entirely shared with its food homologues from apple and hazelnut. Thus, it is important to tackle pollen-related food allergies from different angles for the generation of effective vaccine candidates to treat birch PFS.

Walnut Allergy in Peanut-Allergic Patients: Significance of Sequential Epitopes of Walnut Homologous to Linear Epitopes of Ara h 1, 2 and 3 in Relation to Clinical Reactivity

Background: Peanut allergy is a frequent and potentially life-threatening food allergy. Despite the large taxonomic distance between the plants, peanut-allergic patients often react to tree nuts such as walnuts. While the allergens of peanut and walnut have a high degree of homology in their amino-acid sequences, it is unknown whether this similarity is responsible for the observed co-reactivity. Therefore, we analyzed the binding of specific IgE antibodies to sequential epitopes of peanut and walnut in peanut-allergic patients with and without walnut allergy. Methods: The IgE binding to previously described sequential epitopes of peanut and the homologous regions of walnut was assessed in 32 peanut-allergic patients using a peptide microarray technology. Twelve patients had a clinically relevant walnut allergy and 20 were tolerant to walnut. Inhibition assays with peanut peptides and corresponding walnut sequences were performed to show specific binding to sequential epitopes. Results: No differences in the recognition of sequential epitopes could be found between peanut-allergic patients with or without walnut allergy. Only a few patients showed IgE binding to walnut sequences that corresponded to sequential epitopes of peanut. In the inhibition assays, no relevant cross-reacting IgE antibodies could be detected for the peptides analyzed. Conclusion: Our results indicate that although they share a rather high degree of homology with the corresponding regions of walnut allergens, the sequence stretches previously identified as sequential IgE binding epitopes of Ara h 1, Ara h 2 and Ara h 3 have no IgE binding equivalents in walnut allergens.

Cross-reactivity of pollen and food allergens: soybean Gly m 4 is a member of the Bet v 1 superfamily and closely resembles yellow lupine proteins

In many cases, patients allergic to birch pollen also show allergic reactions after ingestion of plant-derived food. This observation is explained on the molecular level by cross-reactivity of IgE antibodies induced by sensitization to the major birch pollen allergen Bet v 1 with homologous food allergens. As IgE antibodies recognize conformational epitopes, a precise structural characterization of the allergens involved is necessary to understand cross-reactivity and thus to develop new methods of allergen-specific immunotherapy for allergic patients. Here we present the three-dimensional solution structure of the soybean allergen Gly m 4, a member of the superfamily of Bet v 1 homologous proteins and a cross-reactant with IgE antibodies originally raised against Bet v 1, as shown by immunoblot inhibition and histamine release assays. Although the overall fold of Gly m 4 is very similar to that of Bet v 1, the three-dimensional structures differ in detail. The Gly m 4 local structures that display those differences are also found in proteins from yellow lupine. The three-dimensional structure of Gly m 4 in combination with immunological data allows us to propose surface patches that might represent cross-reactive epitopes.

A study on the immunological basis of the dissociation between type I-hypersensitivity skin reactions to Blomia tropicalis antigens and serum anti-B. tropicalis IgE antibodies

BackgroundTwo conditions are used as markers of atopy: the presence of circulating anti-allergen IgE antibodies and the presence of positive skin prick test (SPT) reactions to allergenic extracts. The correlation between these conditions is not absolute. This study aimed at investigating immunological parameters that may mediate this lack of correlation. Individuals whose sera contained anti-B. tropicalis extract IgE antibodies (α-BtE IgE) were divided into two groups, according to the presence or absence of skin reactivity to B. tropicalis extract (BtE). The following parameters were investigated: total IgE levels; α-BtE IgE levels; an arbitrary α-BtE IgE/total IgE ratio; the proportion of carbohydrate-reactive α-BtE IgE; the proportion of α-BtE IgE that reacted with Ascaris lumbricoides extract (AlE); the production of IL-10 by BtE- and AlE-stimulated peripheral blood cells (PBMC).ResultsTotal IgE levels were similar in the two groups, but α-BtE IgE was significantly higher in the SPT-positive group (SPT+). A large overlap of α-BtE IgE levels was found in individuals of both groups, indicating that these levels alone cannot account for the differences in SPT outcome. Individuals of the two groups did not differ, statistically, in the proportion of α-BtE IgE that reacted with carbohydrate and in the production of IL-10 by BtE- and AlE-stimulated PBMC. Both groups had part of α-BtE IgE activity absorbed out by AlE, indicating the existence of cross-reactive IgE antibodies. However, the α-BtE IgE from the SPT-negative individuals (SPT-) was more absorbed with AlE than the α-BtE IgE from the SPT+ individuals. This finding may be ascribed to avidity differences of the α-BtE IgE that is present in the two groups of individuals, and could occur if at least part of the α-BtE IgE from the SPT- individuals were elicited by A. lumbricoides infection.ConclusionThe present results suggest that a low ratio of specific IgE to total IgE levels (in a minority of individuals), and differences in α-BtE IgE avidities (which would have high affinities for A. lumbricoides antigens in SPT- than in SPT+ individuals) may play a role in the down-modulation of type-I hypersensitivity reaction against aeroallergens described in helminth-infected individuals.

Structure of the major carrot allergen Dau c 1

Dau c 1 is a major allergen of carrot (Daucus carota) which displays IgE cross-reactivity with the homologous major birch-pollen allergen Bet v 1. The crystal structure of Dau c 1 has been determined to a resolution of 2.7 A, revealing tight dimers. The structure of Dau c 1 is similar to those of the major allergens from celery, Api g 1, and birch pollen, Bet v 1. Electron density has been observed in the hydrophobic cavity of each monomer and has been modelled with polyethylene glycol oligomers of varying length. Comparison of the surface topology and physicochemical properties of Dau c 1 and Bet v 1 revealed that they may have some, but not all, epitopes in common. This is in agreement with the observation that the majority of carrot-allergic patients have Bet v 1 cross-reactive IgE antibodies, whereas others have Dau c 1-specific IgE antibodies which do not recognize Bet v 1.

Diagnostic evaluation of food-related allergic diseases

Food allergy is a serious and potentially life-threatening problem for an estimated 6% of children and 3.7% of adults. This review examines the diagnostic process that begins with a patient's history and physical examination. If the suspicion of IgE-mediated food allergy is compelling based on the history, skin and serology tests are routinely performed to provide confirmation for the presence of food-specific IgE antibody. In selected cases, a provocation challenge may be required as a definitive or gold standard reference test for confirmation of IgE mediated reactions to food. Variables that influence the accuracy of each of the diagnostic algorithm phases are discussed. The clinical significance of food allergen-specific IgE antibody cross-reactivity and IgE antibody epitope mapping of food allergens is overviewed. The advantages and limitations of the various diagnostic procedures are examined with an emphasis on future trends in technology and reagents.

Cross-reactivity of pollen and food allergens: soybean Gly m 4 is a member of the Bet v 1 superfamily and closely resembles yellow lupine proteins

In many cases, patients allergic to birch pollen also show allergic reactions after ingestion of certain fruits or vegetables. This observation is explained at the molecular level by cross-reactivity of IgE antibodies induced by sensitization to the major birch pollen allergen Bet v 1 with homologous food allergens. As IgE antibodies recognize conformational epitopes, a precise structural characterization of the allergens involved is necessary to understand cross-reactivity and thus to develop new methods of allergen-specific immunotherapy for allergic patients. Here, we report the three-dimensional solution structure of the soybean allergen Gly m 4, a member of the superfamily of Bet v 1 homologous proteins and a cross-reactant with IgE antibodies originally raised against Bet v 1 as shown by immunoblot inhibition and histamine release assays. Although the overall fold of Gly m 4 is very similar to that of Bet v 1, the three-dimensional structures of these proteins differ in detail. The Gly m 4 local structures that display those differences are also found in proteins from yellow lupine with known physiological function. The three-dimensional structure of Gly m 4 may thus shed some light on the physiological function of this subgroup of PR10 proteins (class 10 of pathogenesis-related proteins) and, in combination with immunological data, allow us to propose surface patches that might represent cross-reactive epitopes.