IgE Antibody Binding Research Articles

A novel IgE epitope-specific antibodies-based sandwich ELISA for sensitive measurement of immunoreactivity changes of peanut allergen Ara h 2 in processed foods.

Peanut is an important source of dietary protein for human beings, but it is also recognized as one of the eight major food allergens. Binding of IgE antibodies to specific epitopes in peanut allergens plays important roles in initiating peanut-allergic reactions, and Ara h 2 is widely considered as the most potent peanut allergen and the best predictor of peanut allergy. Therefore, Ara h 2 IgE epitopes can serve as useful biomarkers for prediction of IgE-binding variations of Ara h 2 and peanut in foods. This study aimed to develop and validate an IgE epitope-specific antibodies (IgE-EsAbs)-based sandwich ELISA (sELISA) for detection of Ara h 2 and measurement of Ara h 2 IgE-immunoreactivity changes in foods. DEAE-Sepharose Fast Flow anion-exchange chromatography combining with SDS-PAGE gel extraction were applied to purify Ara h 2 from raw peanut. Hybridoma and epitope vaccine techniques were employed to generate a monoclonal antibody against a major IgE epitope of Ara h 2 and a polyclonal antibody against 12 IgE epitopes of Ara h 2, respectively. ELISA was carried out to evaluate the target binding and specificity of the generated IgE-EsAbs. Subsequently, IgE-EsAbs-based sELISA was developed to detect Ara h 2 and its allergenic residues in food samples. The IgE-binding capacity of Ara h 2 and peanut in foods was determined by competitive ELISA. The dose-effect relationship between the Ara h 2 IgE epitope content and Ara h 2 (or peanut) IgE-binding ability was further established to validate the reliability of the developed sELISA in measuring IgE-binding variations of Ara h 2 and peanut in foods. The obtained Ara h 2 had a purity of 94.44%. Antibody characterization revealed that the IgE-EsAbs recognized the target IgE epitope(s) of Ara h 2 and exhibited high specificity. Accordingly, an IgE-EsAbs-based sELISA using these antibodies was able to detect Ara h 2 and its allergenic residues in food samples, with high sensitivity (a limit of detection of 0.98 ng/mL), accuracy (a mean bias of 0.88%), precision (relative standard deviation < 16.50%), specificity, and recovery (an average recovery of 98.28%). Moreover, the developed sELISA could predict IgE-binding variations of Ara h 2 and peanut in foods, as verified by using sera IgE derived from peanut-allergic individuals. This novel immunoassay could be a user-friendly method to monitor low level of Ara h 2 and to preliminary predict in vitro potential allergenicity of Ara h 2 and peanut in processed foods.

Dual assessment of total binding and antigen avidity of specific IgE antibody better predicts outcomes of oral food challenge in children

Dual assessment of total binding and antigen avidity of specific IgE antibody better predicts outcomes of oral food challenge in children

Local nasal immunotherapy with birch pollen-galactomannan conjugate-containing ointment in mice and humans

BackgroundAllergen immunotherapy (AIT) is the only disease-modifying treatment for immunoglobulin (Ig) E-mediated allergy. Owing to the high prevalence and early onset of hay fever and pollen-food allergy syndrome (PFAS), a safer and simpler treatment method than conventional AIT is needed. To develop a local nasal immunotherapy using an ointment containing hypoallergenic pollen and assess its efficacy in mice and healthy humans. MethodsHypoallergenicity was achieved by combining pollen and galactomannan through the Maillard reaction to create birch pollen-galactomannan conjugate (BP-GMC). The binding of galactomannan to Bet v 1 was confirmed using electrophoresis and Western blotting (WB). Binding of specific IgE antibodies to BP-GMC was verified using enzyme-linked immunosorbent assay (ELISA) and basophil activation test (BAT). The localization of BP-GMC absorption was confirmed using a BALB/c mouse model. BP-GMC mixed with white petrolatum was intranasally administered to 10 healthy individuals (active drugs, 8; placebo, 2) for 14 days. ResultsIn electrophoresis and WB, no 17-kDa band was observed. In ELISA and BAT, BP-GMC did not react to specific IgE but was bound to IgA and IgG. In the mouse model, BP-GMC was detected in nasopharyngeal-associated lymphoid tissues. In the active drug group, the salivary-specific IgA level significantly increased on day 15 (p = 0.0299), while the serum-specific IgG level significantly increased on day 85 (p = 0.0006). ConclusionsThe BP-GMC ointment rapidly produced antagonistic antibodies against IgE; it is safe and easy to use and might serve as a therapeutic antigen for hay fever and PFAS.

Immunochemical Characterization of Salix alba (S. alba) Pollen Allergens and Evaluation of the Cross-Reactivity Pattern with Common Allergenic Pollen Grains

BackgroundPollens, particularly tree and plant pollens, are one of the major causes of allergic respiratory diseases worldwide. Allergy to pollens of different species of Salix trees has been reported in various regions of the world. The most common type of Salix tree in Iran is white willow (Salix alba). ObjectivesThis study aimed to identify and determine the immunochemical characteristics of allergenic proteins in S. alba tree pollen extract using SDS-PAGE and IgE- immunoblotting methods. Moreover, the cross-reaction pattern of the specific IgE antibody of S. alba tree pollen proteins with pollen allergens of common allergenic trees, i.e., Populus nigra (P. nigra), Cupressus sempervirens (C. sempervirens), Pinus brutia (P. brutia) and Platanus orientalis (P. orientalis) in the region was investigated. MethodsThe reaction of allergenic proteins in S. alba pollen extract with specific IgE antibodies in patients' sera was investigated using SDS-PAGE and IgE-immunoblotting methods. The cross-reaction of specific IgE antibodies of the proteins present in S. alba pollen extract with pollen allergens of common allergenic trees in the region was investigated using ELISA and immunoblotting inhibition methods. In silico methods such as phylogenetic tree drawing and alignment of amino acid sequences were used to examine the evolutionary relationship and homology structure of common allergenic proteins (Panallergens) responsible for cross reactions. ResultsMore than 11 protein bands binding to specific IgE antibodies in patients' sera with a molecular weight between 13 and 95 kDa were identified in the S. alba tree pollen extract. ELISA and immunoblotting inhibition results showed that P. nigra extract could inhibit the binding of IgE antibodies to S. alba pollen extract proteins to a greater extent than C. sempervirens, P. brutia, and P. orientalis tree extracts. In silico methods investigated the results of ELISA and immunoblotting inhibition methods. Moreover, a high structural homology and evolutionary relationship were observed between S. alba and P. nigra tree pollen panallergens. ConclusionIn this study, it was found that more than 80 % of the sensitive patients who were examined had specific IgE antibodies reacting with the approximately a 15 kDa-protein present in the S. alba pollen extract. Furthermore, the specific IgE-binding proteins found in the pollens of S. alba and P. nigra trees had relative structural homology, and it is likely that if recombinant forms are produced, they can be used for diagnostic and therapeutic purposes for both of the trees.

Potential role for a Nematode Pan Allergen (NPA) in Tropical Pulmonary Eosinophilia (TPE)

Abstract Tropical Pulmonary Eosinophilia (TPE) is an asthma-like hyper-responsive syndrome characterized by accumulation of a high number of eosinophils in the lungs leading to severe respiratory morbidity in patients infected with lymphatic filariasis (LF), a helminth parasitic infection that affects 51 million people in 47 different countries worldwide. Subjects showing TPE also have circulating microfilariae (larval stages of LF) and a high titer of parasite-specific IgE in their blood. IgE and eosinophils are thought to play a major role in TPE pathology. However, specific antigens that are released from microfilariae responsible for generating the IgE antibodies in TPE are not known. Therefore, in this study, we screened a phage displayed cDNA expression library of Wuchereria bancrofti microfilaria with human monoclonal IgE antibodies generated from B cells isolated from TPE patients. The iterative screening identified WbNPA (Nematode Pan Allergen) and WbTCTP (Translationally Controlled Tumor Protein) as IgE antibody binding antigens. Subsequent analysis showed that rWbNPA and rWbTCTP can result in the release of histamine from mast cells in an IgE-dependent and independent manner. rWbNPA can induce accumulation of eosinophils in the peritoneal cavity of mice and can trigger the secretion of IL-2 and TNF-α from alveolar macrophages. These results suggest that WbNPA and WbTCTP have a potential role in the pathology of TPE in LF infections.

Epitope Structural Analysis of Dust Mite Allergen Der p 2 with Human IgE Monoclonal Antibodies

Human IgE monoclonal antibodies (hIgE mAb) against Der p 2 have been developed using human hybridoma technology, which contain the natural pairing of heavy and light chains and allow for mapping and analysis of IgE antibody binding epitopes.

Ascorbylation of a Reactive Cysteine in the Major Apple Allergen Mal d 1.

The protein Mal d 1 is responsible for most allergic reactions to apples (Malus domestica) in the northern hemisphere. Mal d 1 contains a cysteine residue on its surface, with its reactive side chain thiol exposed to the surrounding food matrix. We show that, in vitro, this cysteine residue is prone to spontaneous chemical modification by ascorbic acid (vitamin C). Using NMR spectroscopy and mass spectrometry, we characterize the chemical structure of the cysteine adduct and provide a three-dimensional structural model of the modified apple allergen. The S-ascorbylated cysteine partially masks a major IgE antibody binding site on the surface of Mal d 1, which attenuates IgE binding in sera of apple-allergic patients. Our results illustrate, from a structural perspective, the role that chemical modifications of allergens with components of the natural food matrix can play.

IgE and IgG Antibodies as Regulators of Mast Cell and Basophil Functions in Food Allergy.

Food allergy is a major health issue, affecting the lives of 8% of U.S. children and their families. There is an urgent need to identify the environmental and endogenous signals that induce and sustain allergic responses to ingested allergens. Acute reactions to foods are triggered by the activation of mast cells and basophils, both of which release inflammatory mediators that lead to a range of clinical manifestations, including gastrointestinal, cutaneous, and respiratory reactions as well as systemic anaphylaxis. Both of these innate effector cell types express the high affinity IgE receptor, FcϵRI, on their surface and are armed for adaptive antigen recognition by very-tightly bound IgE antibodies which, when cross-linked by polyvalent allergen, trigger degranulation. These cells also express inhibitory receptors, including the IgG Fc receptor, FcγRIIb, that suppress their IgE-mediated activation. Recent studies have shown that natural resolution of food allergies is associated with increasing food-specific IgG levels. Furthermore, oral immunotherapy, the sequential administration of incrementally increasing doses of food allergen, is accompanied by the strong induction of allergen-specific IgG antibodies in both human subjects and murine models. These can deliver inhibitory signals via FcγRIIb that block IgE-induced immediate food reactions. In addition to their role in mediating immediate hypersensitivity reactions, mast cells and basophils serve separate but critical functions as adjuvants for type 2 immunity in food allergy. Mast cells and basophils, activated by IgE, are key sources of IL-4 that tilts the immune balance away from tolerance and towards type 2 immunity by promoting the induction of Th2 cells along with the innate effectors of type 2 immunity, ILC2s, while suppressing the development of regulatory T cells and driving their subversion to a pathogenic pro-Th2 phenotype. This adjuvant effect of mast cells and basophils is suppressed when inhibitory signals are delivered by IgG antibodies signaling via FcγRIIb. This review summarizes current understanding of the immunoregulatory effects of mast cells and basophils and how these functions are modulated by IgE and IgG antibodies. Understanding these pathways could provide important insights into innovative strategies for preventing and/or reversing food allergy in patients.

Bos d 11 in baked milk poses a risk for adverse reactions in milk-allergic patients.

Patients are commonly challenged with foods containing baked milk, for example muffins, yet little is known about the specific allergen content of muffins used in milk challenges or of the effect that baking has on allergenicity. Our objective was to compare the levels of major milk allergens in uncooked and baked muffins using monoclonal immunoassays and IgE antibody binding before and after baking. Uncooked and baked muffins were prepared using recipes from Mount Sinai and Imperial College. Allergen levels were compared by ELISA for Bos d 5 (β-lactoglobulin) and Bos d 11 (β-casein). IgE reactivity was assessed using sera from milk-sensitized donors in direct binding and inhibition ELISA. Bos d 5 was reduced from 680µg/g in uncooked muffin mix to 0.17µg/g in baked muffins, representing a >99% decrease after baking. Conversely, Bos d 11 levels in baked muffin remained high and only decreased by 30% from a mean of 4249µg/g in uncooked muffin mix to 2961µg/g when baked (~181mg Bos d 11 per muffin). Baked muffins retained ~70% of the IgE binding to uncooked muffin mix. Baked muffin extract inhibited IgE binding to uncooked muffin mix by up to 80%, demonstrating retention of in vitro IgE reactivity. High levels of Bos d 11 in baked muffins pose a risk for adverse reactions, especially in patients who have high anti-casein IgE antibodies.

Characterization of a 7 kDa pollen allergen belonging to the gibberellin‐regulated protein family from three Cupressaceae species

Severe allergy to fruits mediated by a 7kDa allergen belonging to the gibberellin-regulated protein (GRP) family is known to be associated with Cupressaceae pollinosis. To identify and characterize Cupressaceae pollen allergens involved in GRP-related fruit allergy. Pru p 7-related proteins from pollen of Cupressus sempervirens, Juniperus ashei and Cryptomeria japonica were identified using a rabbit anti-Pru p 7 antiserum, purified chromatographically and sequenced by mass spectrometry and bioinformatic comparisons. The Csempervirens protein was produced as a recombinant allergen in Pichia pastoris. IgE antibody binding to pollen GRP proteins was analysed in a peach allergic (n=54) and a cypress pollen allergic (n=88) patient population from southern France using ImmunoCAP. In each of the three Cupressaceae species studied, a 7kDa pollen protein related to Pru p 7 was identified and found to comprise an amino acid sequence of 63 residues in length, 92%-98% identical to each other and 67%-68% identical to Pru p 7. The Csempervirens, Jashei and Cjaponica GRP allergens have been officially recognized by the WHO/IUIS Allergen Nomenclature Sub-Committee and named Cup s 7, Jun a 7 and Cry j 7, respectively. Recombinant Cup s 7 showed IgE antibody binding capacity comparable to that of the purified natural allergen. Among 51 peach allergic subjects sensitized to Pru p 7, substantially higher levels of IgE to Cup s 7 than to Pru p 7 were found. Further, the pollen protein was able to completely outcompete IgE binding to Pru p 7, while the reverse competition effect was modest, consistent with primary sensitization by the pollen allergen. Pru p 7-related pollen allergens from three Cupressaceae species have been characterized and may become useful for the identification of pollinosis patients at risk of developing severe fruit allergy.

Hydrolase-treated royal jelly attenuates LPS-induced inflammation and IgE-antigen-mediated allergic reaction

Background: Royal jelly (RJ) is one of the most effectual and beneficial remedies for human beings and currently utilized in many sectors, ranging from the pharmaceutical and food industries to cosmetic and manufacturing sectors due to RJ possessing many bio-therapeutical activities including anti-tumor, antimicrobial and antioxidant activities, vasodilative and hypotensive activities, as well as growth-stimulating, infection-preventing, anti-hypercholesterolemic and anti-inflammatory activities. However, some reports showing direct consumption of RJ can lead to severe allergic reaction and has been linked with acute asthma, dermatitis, and life-threatening anaphylaxis. Thus, this research purposes to explore the potential anti-inflammatory and anti-allergic activities of hydrolyzed RJ as a function of enzyme and the extent of hydrolysis.Methods: RJ was enzymatically hydrolyzed with three commercial enzymes (AlcalaseÒ, FlavourzymeÒ and ProtamexÒ). Anti-inflammatory activity of the hydrolysates was measured by their inhibitory effect on nitric oxide (NO) production of lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. Anti-allergy was determined from the ability of the hydrolysates to inhibit b-hexsosaminidase (b-HEX) release from RBL-2H3 mast cells. Cytotoxicity was also investigated in both RAW264.7 macrophage cells and RBL-2H3 mast cells.Results: The electrophoretic profiles indicated that AlcalaseÒ and FlavourzymeÒ hydrolysates did not show the presence of proteins causing allergic reaction after 60 mins of hydrolysis while these allergens disappeared from ProtamexÒ hydrolysate at the hydrolysis time of 240 min. It was observed that hydrolyzed RJ showed no toxicity on RAW264.7 and RBL-2H3 cells. With the progression of hydrolysis, IC50 values of NO production inhibition significantly decreased while degree of hydrolysis (DH) was increased in all hydrolyzed samples (p &lt; 0.05). Results of b-HEX release inhibition were found in the same fashion. FlavourzymeÒ hydrolysate at the 240 min time point effectively mitigated the oxidative stress and protected DNA in a dose dependent manner.Conclusions: RJ hydrolysates from FlavourzymeÒ resulted in peptides with anti-inflammatory activity as determined by the inhibition of NO production in LPS-stimulated RAW264.7 macrophage cells and anti-allergic property as measured by the suppression of degranulation of sensitized RBL-2H3 cells. Anti-inflammatory effect may be due to their anti-oxidative capability. Inhibition of b-HEX release may be due to their membrane-stabilizing effects or/and blockade of IgE antibody binding to its receptors.Keywords: anti-inflammation, enzymatic hydrolysate, royal jelly, anti-allergy

Conservation Analysis of B-Cell Allergen Epitopes to Predict Clinical Cross-Reactivity Between Shellfish and Inhalant Invertebrate Allergens.

Understanding and predicting an individual's clinical cross-reactivity to related allergens is a key to better management, treatment and progression of novel therapeutics for food allergy. In food allergy, clinical cross-reactivity is observed in patients reacting to unexpected allergen sources containing the same allergenic protein or antibody binding patches (epitopes), often resulting in severe allergic reactions. Shellfish allergy affects up to 2% of the world population and persists for life in most patients. The diagnosis of shellfish allergy is however often challenging due to reported clinical cross-reactivity to other invertebrates including mites and cockroaches. Prediction of cross-reactivity can be achieved utilizing an in-depth analysis of a few selected IgE-antibody binding epitopes. We combined available experimentally proven IgE-binding epitopes with informatics-based cross-reactivity prediction modeling to assist in the identification of clinical cross-reactive biomarkers on shellfish allergens. This knowledge can be translated into prevention and treatment of allergic diseases. To overcome the problem of predicting IgE cross-reactivity of shellfish allergens we developed an epitope conservation model using IgE binding epitopes available in the Immune Epitope Database and Analysis Resource (http://www.iedb.org/). We applied this method to a set of four different shrimp allergens, and successfully identified several non-cross-reactive as well as cross-reactive epitopes, which have been experimentally established to cross-react. Based on these findings we suggest that this method can be used for advanced component-resolved-diagnosis to identify patients sensitized to a specific shellfish group and distinguish from patients with extensive cross-reactivity to ingested and inhaled allergens from invertebrate sources.

IgE and IgG4 binding to lentil epitopes in children with red and green lentil allergy.

The consumption of lentil is common in the Mediterranean area and is one of the causes of IgE-mediated food allergy in many countries. Len c 1 is a well-defined allergen of lentil and approximately 80% of the patients with lentil allergy recognize the purified Len c 1 protein. We sought to identify IgE and IgG4 sequential epitopes of Len c 1 in patients with red and/or green lentil allergy. We also aimed to determine IgE and IgG4 binding differences between those patients who had outgrown or remained reactive to lentil. Children with IgE-mediated lentil allergy were included in the study. We applied a microarray immunoassay to determine the characterization of positive IgE and IgG4 binding to Len c 1 epitopes in the patients' sera. The peptides specifically recognized by IgE and IgG4 antibodies were mainly detected between peptides 107 and 135 of Len c 1. The signal intensities of positive epitopes were significantly greater in reactive patients than tolerant ones (P=.008 for IgE and P=.002 for IgG4). Moreover, IgE and IgG4 antibodies bound largely the same sequential epitopes in patients who remained reactive or outgrew their allergy. IgG4-binding epitopes in lentil allergy were identified and IgE and IgG4 binding to epitopes in both red and green lentils was compared. Our data regarding signal intensity differences between reactive and outgrown patients and overlap binding of IgE and IgG4 antibodies may be important for the development of more accurate diagnostic tests and understanding of natural tolerance development.

A Human IgE Antibody Binding Site on Der p 2 for the Design of a Recombinant Allergen for Immunotherapy.

Der p 2 is one of the most important allergens from the house dust mite Dermatophagoides pteronyssinus Identification of human IgE Ab binding epitopes can be used for rational design of allergens with reduced IgE reactivity for therapy. Antigenic analysis of Der p 2 was performed by site-directed mutagenesis based on the x-ray crystal structure of the allergen in complex with a Fab from the murine IgG mAb 7A1 that binds an epitope overlapping with human IgE binding sites. Conformational changes upon Ab binding were confirmed by nuclear magnetic resonance using a 7A1-single-chain variable fragment. In addition, a human IgE Ab construct that interferes with mAb 7A1 binding was isolated from a combinatorial phage-display library constructed from a mite-allergic patient and expressed as two recombinant forms (single-chain Fab in Pichia pastoris and Fab in Escherichia coli). These two IgE Ab constructs and the mAb 7A1 failed to recognize two Der p 2 epitope double mutants designed to abolish the allergen-Ab interaction while preserving the fold necessary to bind Abs at other sites of the allergen surface. A 10-100-fold reduction in binding of IgE from allergic subjects to the mutants additionally showed that the residues mutated were involved in IgE Ab binding. In summary, mutagenesis of a Der p 2 epitope defined by x-ray crystallography revealed an IgE Ab binding site that will be considered for the design of hypoallergens for immunotherapy.

Effects of Ser47-Point Mutation on Conformation Structure and Allergenicity of the Allergen of Der p 2, a Major House Dust Mite Allergen.

PurposeHypoallergenic recombinant Der p 2 has been produced by various genetic manipulations, but mutation of a naturally polymorphic amino acid residue known to affect IgE binding has not been studied. This study aimed to determine the effect of a point mutation (S47W) of residue 47 of Der p 2 on its structure and immunoglobulin (Ig) E binding. Its ability to induce pro-inflammatory responses and to induce blocking IgG antibody was also determined.MethodsS47 of recombinant Der p 2.0110, one of the predominant variants in Bangkok, was mutated to W (S47W). S47W secreted from Pichia pastoris was examined for secondary structure and for the formation of a hydrophobic cavity by 8-Anilino-1-naphthalenesulfonic acid (ANS) staining. Monoclonal and human IgE-antibody binding was determined by enzyme-linked immunosorbent assay. Allergen-induced degranulation by human epsilon receptor expressed-rat basophil was determined. Stimulation of the pro-inflammatory cytokine interleukin (IL)-8 release from human bronchial epithelial (BEAS2B) cells and inhibition of IgE binding to the wild type allergen by S47W-induced IgG were determined.ResultsS47W reduced secondary structure and failed to bind the hydrophobic ANS ligand as well as a monoclonal antibody known to be dependent on the nature of the side chain of residue 114 in an adjacent loop. It could also not stimulate IL-8 release from BEAS2B cells. IgE from house dust mite (HDM)-allergic Thais bound S47W with 100-fold weaker avidity, whereas IgE of HDM-allergic Australians did not. S47W still induced basophil degranulation, although requiring higher concentrations for some subjects. Anti-S47W antiserum-immunized mice blocked the binding of human IgE to wild type Der p 2.ConclusionsThe mutant S47W had altered structure and reduced ability to stimulate pro-inflammatory responses and to bind IgE, but retained its ability to induce blocking antibodies. It thus represents a hypoallergen produced by a single mutation of a non-solvent-accessible amino acid.

Predicting development of sustained unresponsiveness to milk oral immunotherapy using epitope-specific antibody binding profiles

In a recent trial of milk oral immunotherapy (MOIT) with or without omalizumab in 55 patients with milk allergy treated for 28months, 44 of 55 subjects passed a 10-g desensitization milk protein challenge; 23 of 55 subjects passed the 10-g sustained unresponsiveness (SU) challenge 8weeks after discontinuing MOIT. We sought to determine whether IgE and IgG4 antibody binding to allergenic milk protein epitopes changes with MOIT and whether this could predict the development of SU. By using a novel high-throughput Luminex-based assay to quantitate IgE and IgG4 antibody binding to 66 sequential epitopes on 5 milk proteins, serum samples from 47 subjects were evaluated before and after MOIT. Machine learning strategies were used to predict whether a subject would have SU after 8weeks of MOIT discontinuation. MOIT profoundly altered IgE and IgG4 binding to epitopes, regardless of treatment outcome. At the initiation of MOIT, subjects achieving SU exhibited significantly less antibody binding to 40 allergenic epitopes than subjects who were desensitized only (false discovery rate≤0.05 and fold change>1.5). Based on baseline epitope-specific antibody binding, we developed predictive models of SU. Using simulations, we show that, on average, IgE-binding epitopes alone perform significantly better than models using standard serum component proteins (average area under the curve, >97% vs 80%). The optimum model using 6 IgE-binding epitopes achieved a 95% area under the curve and 87% accuracy. Despite the relatively small sample size, we have shown that by measuring the epitope repertoire, we can build reliable models to predict the probability of SU after MOIT. Baseline epitope profiles appear more predictive of MOIT response than those based on serum component proteins.

Der p 5 allergen from house dust mite: first epitope mapping of rabbit IgG blocking antibodies.

Der p 5 is one of the important house dust mite allergens in Algeria; this allergen is frequently recognized by patients with allergic asthma. However, there is no information on its IgG–binding epitopes. In the present study, rabbits were immunized with recombinant Der p 5 allergen, and serum samples were obtained. Recognition of linear IgG epitopes of Der p 5 was determined using synthesized peptides derived from the allergen sequence. The results showed that serum from immunized rabbits recognized three linear epitopes from Der p 5 (28EDKKHDYQNEFDFLLMERIHEQIK43), (37IHEQIKKGELALFYLQEQ55) and (92LMQRKDLDIFEQYNLEMAKKS112). More interestingly, we observed that the 92L-S112 amino acid sequence is well recognized by both IgE and IgG antibodies. Der p 5 stimulates the synthesis of specific IgG antibodies which recognize common but also novel epitopes compared to IgE antibody binding. Indeed, the potential to induce IgG antibodies can be used to inhibit human IgE binding to allergens which may be part of the mechanism of action of specific immunotherapy.

A 70-KD PROTEIN MAY PLAY A ROLE IN CHINESE BIRCH POLLEN ALLERGY

Introduction Birch pollen allergy is a common cause of spring pollinosis in China. Only the major allergen (Bet v 1) has been fully characterized and there is little research on birch pollen allergen in China. Methods Human serum was collected from patients with a documented clinical allergy in the Allergy Department. Birch pollen induced airway inflammation models in BALB/c mice were developed. Birch pollen extract was analyzed by SDS-PAGE. Western blot analysis was applied to both mice and human serum. Mass spectrometry was used to identify the IgE-binding bands in birch pollen. Results Chinese birch pollen extract (BPE) showed multiple protein bands clear at 17 kDa, 28 kDa, 36 kDa and 70 kDa. Patient serum exhibited IgE antibody binding against 17 kDa, 36 kDa and 70 kDa proteins, while healthy control serum reacted no bands. Interestingly, we established a birch pollen induced mice model. Compared with a PBS control group, birch pollen sensitized and challenged BALB/c mice developed airway responsiveness. In the bronchoalveolar lavage fluid (BALF), IL4, IL10 and IL17 were significantly higher. The levels of anti-BPE IgE, IgG1 and IgG2a also increased significantly. Histologic analyses showed that these mice had peribronchial infiltration of inflammatory cells and mucosal hyperplasia when challenged with BPE. Mice serum pool showed strong reactions to 17 kDa, 70 kDa and 100 kDa proteins. Mass spectrometry data suggests that the 70k Da protein may belong to the HSP 70 family. Conclusions A 70 kDa protein potentially belonging to the HSP 70 family plays a significant role in Chinese birch pollen allergy.

Allergen content in German cockroach extracts and sensitization profiles to a new expanded set of cockroach allergens determine in vitro extract potency for IgE reactivity

Cockroach allergens are an important cause of IgE-mediated sensitization in inner-city asthmatic patients. However, cockroach extracts used for diagnosis and immunotherapy are not standardized. We sought to determine the allergen content of nonstandardized German cockroach extracts and the levels of sensitization to an expanded set of cockroach allergens as determinants of invitro extract potency for IgE reactivity. Twelve German cockroach extracts were compared for allergen content and potency of IgE reactivity. Bla g 1, Bla g 2, and Bla g 5 were measured by using immunoassays. IgE antibody levels to 8 purified recombinant allergens from groups 1, 2, 4, 5, 6, 7, 9, and 11 were measured by using ImmunoCAP. IgE antibody binding inhibition assays were performed to assess extract invitro potencies (concentration inhibiting 30% of the total IgE antibody-binding inhibition) relative to an arbitrarily selected reference extract in 5 patients with cockroach allergy. Allergen levels were highly variable. Three new major allergens (groups 6, 9, and 11), were identified among highly cockroach-sensitized subjects (CAP class≥3). Sensitization profiles were unique per subject without immunodominant allergens. The sum of IgE to 8 allergen components showed a good correlation with cockroach-specific IgE levels (r=0.88, P<.001). Invitro potencies varied among different extracts per subject and among subjects for each extract. The invitro potency of German cockroach extracts for IgE reactivity depends on allergen content and allergen-specific IgE titers of patients with cockroach allergy. These factors are relevant for selection of potent extracts to be used for immunotherapy and for the design and interpretation of data from immunotherapy trials.

Acidic polypeptides A1a, A3 and A4 of Gly m 6 (glycinin) are allergenic for piglets

Gly m 6 (glycinin) is one of the major antigenic proteins in soybeans responsible for transient hypersensitivity to soybean meal in weaned piglets. The globulin is a hexamer consisting of subunits containing basic and acidic polypeptides. Multiple acidic polypeptides have long been demonstrated to be allergens for humans and play a key role in the overall allergenicity of Gly m 6. To date, knowledge on the allergenicity of the acidic polypeptides for piglets is very limited. The purpose of this study was to identify the acidic polypeptides that were allergenic for piglets and to characterize these acidic polypeptides by ELISA, western blot, skin prick and basophile histamine release test. The IgG and IgE antibody binding capacities of the acidic polypeptides of Gly m 6 were determined using ELISA and western blot analysis with sera from Gly m 6 sensitized piglets. Skin prick test and basophile histamine release test were conducted to measure the effector cell response to the polypeptides. Specific IgG and IgE antibodies against A1a, A3 and A4 of Gly m 6 were identified in the sera of Gly m 6 sensitized piglets. Meanwhile, positive skin prick test and specific histamine release responses were also induced by the acidic polypeptide A1a, A3 and A4 of Gly m 6 from the basophiles of Gly m 6 sensitized piglets. The results demonstrate that the acidic polypeptide A1a, A3 and A4 of Gly m 6 are allergenic for piglets.