Component-resolved diagnosis of baker's allergy based on specific IgE to recombinant wheat flour proteins

Detection of Sensitization Profiles with Cellular In Vitro Tests in Wheat Allergy Dependent on Augmentation Factors (WALDA)

Wheat allergy dependent on augmentation factors (WALDA) is the most common gluten allergy in adults. IgE-mediated sensitizations are directed towards ω5-gliadin but also to other wheat allergens. The value of the different in vitro cellular tests, namely the basophil activation test (BAT) and the active (aBHRA) and passive basophil histamine-release assays (pBHRA), in the detection of sensitization profiles beyond ω5-gliadin has not been compared. Therefore, 13 patients with challenge-confirmed, ω5-gliadin-positive WALDA and 11 healthy controls were enrolled. Specific IgE (sIgE), skin prick tests, BATs, aBHRA, and pBHRA were performed with allergen test solutions derived from wheat and other cereals, and results were analyzed and compared. This study reveals a distinct and highly individual reactivity of ω5-gliadin-positive WALDA patients to a range of wheat allergens beyond ω5-gliadin in cellular in vitro tests and SPT. In the BAT, for all tested allergens (gluten, high-molecular-weight glutenin subunits, α-amylase/trypsin inhibitors (ATIs), alcohol-free wheat beer, hydrolyzed wheat proteins (HWPs), rye gluten and secalins), basophil activation in patients was significantly higher than in controls (p = 0.004-p < 0.001). Similarly, significant histamine release was detected in the aBHRA for all test substances, exceeding the cut-off of 10 ng/mL in all tested allergens in 50% of patients. The dependency of tests on sIgE levels against ω5-gliadin differed; in the pBHRA, histamine release to any test substances could only be detected in patients with sIgE against ω5-gliadin ≥ 7.7 kU/L, whereas aBHRA also showed high reactivity in less sensitized patients. In most patients, reactivity to HWPs, ATIs, and rye allergens was observed. Additionally, alcohol-free wheat beer was first described as a promising test substance in ω5-gliadin-positive WALDA. Thus, BAT and aBHRA are valuable tools for the identification of sensitization profiles in WALDA.

In silico approaches for the identification of potential allergens among hypothetical proteins from Alternaria alternata and its functional annotation

Direct exposure to the fungal species Alternaria alternata is a major risk factor for the development of asthma, allergic rhinitis, and inflammation. As of November 23rd 2020, the NCBI protein database showed 11,227 proteins from A. alternata genome as hypothetical proteins (HPs). Allergens are the main causative of several life-threatening diseases, especially in fungal infections. Therefore, the main aim of the study is to identify the potentially allergenic inducible proteins from the HPs in A. alternata and their associated functional assignment for the complete understanding of the complex biological systems at the molecular level. AlgPred and Structural Database of Allergenic Proteins (SDAP) were used for the prediction of potential allergens from the HPs of A. alternata. While analyzing the proteome data, 29 potential allergens were predicted by AlgPred and further screening in SDAP confirmed the allergic response of 10 proteins. Extensive bioinformatics tools including protein family classification, sequence-function relationship, protein motif discovery, pathway interactions, and intrinsic features from the amino acid sequence were used to successfully predict the probable functions of the 10 HPs. The functions of the HPs are characterized as chitin-binding, ribosomal protein P1, thaumatin, glycosyl hydrolase, and NOB1 proteins. The subcellular localization and signal peptide prediction of these 10 proteins has further provided additional information on localization and function. The allergens prediction and functional annotation of the 10 proteins may facilitate a better understanding of the allergenic mechanism of A. alternata in asthma and other diseases. The functional domain level insights and predicted structural features of the allergenic proteins help to understand the pathogenesis and host immune tolerance. The outcomes of the study would aid in the development of specific drugs to combat A. alternata infections.

Prospects for developing allergen-depleted food crops

In addition to the challenge of meeting global demand for food production, there are increasing concerns about food safety and the need to protect consumer health from the negative effects of foodborne allergies. Certain bio-molecules (usually proteins) present in food can act as allergens that trigger unusual immunological reactions, with potentially life-threatening consequences. The relentless working lifestyles of the modern era often incorporate poor eating habits that include readymade prepackaged and processed foods, which contain additives such as peanuts, tree nuts, wheat, and soy-based products, rather than traditional home cooking. Of the predominant allergenic foods (soybean, wheat, fish, peanut, shellfish, tree nuts, eggs, and milk), peanuts (Arachis hypogaea) are the best characterized source of allergens, followed by tree nuts (Juglans regia, Prunus amygdalus, Corylus avellana, Carya illinoinensis, Anacardium occidentale, Pistacia vera, Bertholletia excels), wheat (Triticum aestivum), soybeans (Glycine max), and kidney beans (Phaseolus vulgaris). The prevalence of food allergies has risen significantly in recent years including chance of accidental exposure to such foods. In contrast, the standards of detection, diagnosis, and cure have not kept pace and unfortunately are often suboptimal. In this review, we mainly focus on the prevalence of allergies associated with peanut, tree nuts, wheat, soybean, and kidney bean, highlighting their physiological properties and functions as well as considering research directions for tailoring allergen gene expression. In particular, we discuss how recent advances in molecular breeding, genetic engineering, and genome editing can be used to develop potential low allergen food crops that protect consumer health.

Cross-reactive epitopes and their role in food allergy

Allergenic cross-reactivity among food allergens complicates the diagnosis and management of food allergy. This can result in many patients being sensitized (having allergen-specific IgE) to foods without exhibiting clinical reactivity. Some food groups such as shellfish, fish, tree nuts, and peanuts have very high rates of cross-reactivity. In contrast, relatively low rates are noted for grains and milk, whereas many other food families have variable rates of cross-reactivity or are not well studied. Although classical cross-reactive carbohydrate determinants are clinically not relevant, α-Gal in red meat through tick bites can lead to severe reactions. Multiple sensitizations to tree nuts complicate the diagnosis and management of patients allergic to peanut and tree nut. This review discusses cross-reactive allergens and cross-reactive carbohydrate determinants in the major food groups, and where available, describes their B-cell and T-cell epitopes. The clinical relevance of these cross-reactive B-cell and T-cell epitopes is highlighted and their possible impact on allergen-specific immunotherapy for food allergy is discussed.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Wheat Amylase Trypsin Inhibitors Aggravate Intestinal Inflammation Associated with Celiac Disease Mediated by Gliadin in BALB/c Mice

Celiac disease (CD) is an autoimmune intestinal disorder caused by the ingestion of gluten in people who carry the susceptible gene. In current celiac disease research, wheat gluten is often the main target of attention, neglecting the role played by non-gluten proteins. This study aimed to describe the effects of wheat amylase trypsin inhibitors (ATI, non-gluten proteins) and gliadin in BALB/c mice while exploring the further role of relevant adjuvants (cholera toxin, polyinosinic: polycytidylic acid and dextran sulfate sodium) intervention. An ex vivo splenocyte and intestinal tissue were collected for analysis of the inflammatory profile. The consumption of gliadin and ATI caused intestinal inflammation in mice. Moreover, the histopathology staining of four intestinal sections (duodenum, jejunum, terminal ileum, and middle colon) indicated that adjuvants, especially polyinosinic: polycytidylic acid, enhanced the villi damage and crypt hyperplasia in co-stimulation with ATI and gliadin murine model. Immunohistochemical results showed that tissue transglutaminase and IL-15 expression were significantly increased in the jejunal tissue of mice treated with ATI and gliadin. Similarly, the expression of inflammatory factors (TNF-α, IL-1β, IL-4, IL-13) and Th1/Th2 balance also showed that the inflammation response was significantly increased after co-stimulation with ATI and gliadin. This study provided new evidence for the role of wheat amylase trypsin inhibitors in the pathogenesis of celiac disease.

Wheat amylase/trypsin inhibitors (ATIs): occurrence, function and health aspects

Amylase/trypsin inhibitors (ATIs) are widely consumed in cereal-based foods and have been implicated in adverse reactions to wheat exposure, such as respiratory and food allergy, and intestinal responses associated with coeliac disease and non-coeliac wheat sensitivity. ATIs occur in multiple isoforms which differ in the amounts present in different types of wheat (including ancient and modern ones). Measuring ATIs and their isoforms is an analytical challenge as is their isolation for use in studies addressing their potential effects on the human body. ATI isoforms differ in their spectrum of bioactive effects in the human gastrointestinal (GI), which may include enzyme inhibition, inflammation and immune responses and of which much is not known. Similarly, although modifications during food processing (exposure to heat, moisture, salt, acid, fermentation) may affect their structure and activity as shown in vitro, it is important to relate these changes to effects that may present in the GI tract. Finally, much of our knowledge of their potential biological effects is based on studies in vitro and in animal models. Validation by human studies using processed foods as commonly consumed is warranted. We conclude that more detailed understanding of these factors may allow the effects of ATIs on human health to be better understood and when possible, to be ameliorated, for example by innovative food processing. We therefore review in short our current knowledge of these proteins, focusing on features which relate to their biological activity and identifying gaps in our knowledge and research priorities.

Glucose/Ribitol Dehydrogenase and 16.9 kDa Class I Heat Shock Protein 1 as Novel Wheat Allergens in Baker’s Respiratory Allergy

Wheat allergens are responsible for symptoms in 60–70% of bakers with work-related allergy, and knowledge, at the molecular level, of this disorder is progressively accumulating. The aim of the present study is to investigate the panel of wheat IgE positivity in allergic Italian bakers, evaluating a possible contribution of novel wheat allergens included in the water/salt soluble fraction. The water/salt-soluble wheat flour proteins from the Italian wheat cultivar Bolero were separated by using 1-DE and 2-DE gel electrophoresis. IgE-binding proteins were detected using the pooled sera of 26 wheat allergic bakers by immunoblotting and directly recognized in Coomassie stained gel. After a preparative electrophoretic step, two enriched fractions were furtherly separated in 2-DE allowing for detection, by Coomassie, of three different proteins in the range of 21–27 kDa that were recognized by the pooled baker’s IgE. Recovered spots were analyzed by nanoHPLC Chip tandem mass spectrometry (MS/MS). The immunodetected spots in 2D were subjected to mass spectrometry (MS) analysis identifying two new allergenic proteins: a glucose/ribitol dehydrogenase and a 16.9 kDa class I heat shock protein 1. Mass spectrometer testing of flour proteins of the wheat cultivars utilized by allergic bakers improves the identification of until now unknown occupational wheat allergens.

The effect of nitrogen fertilization on the expression of protein in wheat and tritordeum varieties using a proteomic approach

Wheat, an essential ingredient for several bakery preparations, is also responsible for gluten-related diseases in sensitive subjects. The effect of the N fertilization rate (80 vs 160 kg N ha^-1) on gluten protein expression profile has been evaluated considering two soft wheats (landrace and modern) and one tritordeum cultivar (cv), grown in the same experimental field in North Italy. The proteins of refined flour were characterized through advanced proteomic approaches, including chromatography (RP-HPLC) and electrophoresis. A static model system was used to simulate in vitro digestion and the digestome peptides were examined by mass spectrometry and in silico approaches, to investigate the celiac and allergenic sequences. The CD-toxic epitopes in the digested samples were quantified by means of a R5 ELISA assay. The N fertilization rate increased the grain protein content, but it did not lead to any difference in gluten composition, with exception of glu/glia ratio in the modern wheat cv. Moreover, the gluten composition and the occurrence of toxic/allergenic epitopes varied to a great extent, according mostly to the genotype. A lower immunoreactivity, determined using R5 ELISA, was detected for the digested tritordeum flours than for the landrace (-51%) or modern (-58%) cvs, while no significant difference was observed for the N rates between each genotype. In silico analysis showed that tritordeum has fewer CD epitopes belonging to the ω-gliadins and a lower LMW-GS than the landrace or modern cv. Tritordeum presented fewer α-gliadin allergenic epitopes than the modern wheat cv. The lower frequency of celiac epitopes in tritordeum, compared to the old and the modern wheat, is probably due to the absence of a D genome.

Allergic sensitization pattern of patients in Brazil

OBJECTIVE

Allergic sensitization is one of the key components for the development of allergies. Polysensitization seems to be related to the persistence and severity of allergic diseases. Furthermore, allergic sensitization has a predictive role in the development of allergies. The aim of this study was to characterize the pattern of sensitization of atopic patients treated at different pediatric allergy referral centers in Brazil.

METHODS

A nation-wide transversal multicenter study collected data on patients attended in Brazil. Peripheral blood samples were collected to determine the serum levels of allergen-specific IgE. If allergen-specific IgE was higher than 0.1 kUA/L, the following specific components were quantified.

RESULTS

A total of 470 individuals were enrolled in the study. Mite sensitization was the most frequent kind in all participants. A high frequency of sensitization to furry animals and grasses featured in the respiratory allergies. Regarding components, there was a predominance of sensitization to Der p 1 and Der p 2. It has been verified that having a food allergy, atopic dermatitis, or multimorbidity are risk factors for the development of more severe allergic disease.

CONCLUSION

Studies on the pattern of allergic sensitization to a specific population offer tools for the more effectual prevention, diagnosis, and treatment of allergic diseases. Sensitization to dust mites house was the most prevalent in the evaluated sample. High rates of sensitization to furry animals also stand out. Patients with food allergy, atopic dermatitis, or multimorbidity appear to be at greater risk for developing more severe allergic diseases.

Allergenicity assessment and allergen profile analysis of different Chinese wheat cultivars

Backgrounds

As one of the most important cereals, wheat (Triticum aestivum) can cause severe allergic reactions, such as baker's asthma, allergic rhinitis, and atopic dermatitis. A growing number of people are developing allergies to Chinese wheat; however, only a few wheat cultivars have been screened on allergenicity in China.

Objective

The aim of the present study was to assess the allergenicity of different Chinese wheat cultivars and characterize wheat allergen profiles of patients with allergic rhinitis.

Methods

We determined protein (soluble protein, gliadin, and glutenin) composition in Chinese wheat by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the immunoglobulin E (IgE) binding capacity by enzyme-linked immunosorbent assay (ELISA) and Western blot using 10 positive sera from wheat allergy patients. We identified 5 gel bands with significant IgE binding capacity using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Results

Soluble protein, albumin, and globulin, showed the highest allergenicity, followed by gliadin, while glutenin only had slight allergenicity. In soluble protein, 5 protein bands with molecular weights of 27, 28, 53, 58, and 62 kDa showed very significant allergenicity. Meanwhile, the relative abundances of 28 kDa-protein and 58 kDa-protein were significantly positively correlated with the IgE-binding capacity of Chinese wheat cultivars, which were identified as rRNA N-glycosidase and β-amylase, respectively, among other proteins in those highly complex gel bands.

Conclusion and clinical relevance

28 kDa-protein (rRNA N-glycosidase) and 58 kDa-protein (β-amylase) were speculated to be the main allergens of Chinese wheat causing baker's asthma and allergic rhinitis. These results provide new insights into the prevention and treatment of wheat allergy and the development of hypoallergenic wheat products, whose clinical significance is worth further evaluation.

Wheat ATIs: Characteristics and Role in Human Disease

Amylase/trypsin-inhibitors (ATIs) comprise about 2–4% of the total wheat grain proteins and may contribute to natural defense against pests and pathogens. However, they are currently among the most widely studied wheat components because of their proposed role in adverse reactions to wheat consumption in humans. ATIs have long been known to contribute to IgE-mediated allergy (notably Bakers' asthma), but interest has increased since 2012 when they were shown to be able to trigger the innate immune system, with attention focused on their role in coeliac disease which affects about 1% of the population and, more recently, in non-coeliac wheat sensitivity which may affect up to 10% of the population. This has led to studies of their structure, inhibitory properties, genetics, control of expression, behavior during processing, effects on human adverse reactions to wheat and, most recently, strategies to modify their expression in the plant using gene editing. We therefore present an integrated account of this range of research, identifying inconsistencies, and gaps in our knowledge and identifying future research needs.

Note 

This paper is the outcome of an invited international ATI expert meeting held in Amsterdam, February 3-5 2020

Occupational Respiratory Allergy: Risk Factors, Diagnosis, and Management

Occupational allergies are among the most common recorded occupational diseases. The skin and the upper and lower respiratory tract are the classical manifestation organs. More than 400 occupational agents are currently documented as being potential "respiratory sensitizers" and new reported causative agents are reported each year. These agents may induce occupational rhinitis (OR) or occupational asthma (OA) and can be divided into high-molecular weight (HMW) and low-molecular weight (LMW) agents. The most common occupational HMW agents are (glycol)proteins found in flour and grains, enzymes, laboratory animals, fish and seafood, molds, and Hevea brasiliensis latex. Typical LMW substances are isocyanates, metals, quaternary ammonium persulfate, acid anhydrides, and cleaning products/disinfectants. Diagnosis of occupational respiratory allergy is made by a combination of medical history, physical examination, positive methacholine challenge result or bronchodilator responsiveness, determination of IgE-mediated sensitization, and specific inhalation challenge tests as the gold standard. Accurate diagnosis of asthma is the first step to managing OA as shown above. Removal from the causative agent is of central importance for the management of OA. The best strategy to avoid OA is primary prevention, ideally by avoiding the use of and exposure to the sensitizer or substituting safer substances for these agents.

Assessment and Management of Occupational Asthma

Exposures at work can give rise to different phenotypes of "work-related asthma." The focus of this review is on the diagnosis and management of sensitizer-induced occupational asthma (OA) caused by either a high- or low-molecular-weight agent encountered in the workplace. The diagnosis of OA remains a challenge for the clinician because there is no simple test with a sufficiently high level of accuracy. Instead, the diagnostic process combines different procedures in a stepwise manner. These procedures include a detailed clinical history, immunologic testing, measurement of lung function parameters and airway inflammatory markers, as well as various methods that relate changes in these functional and inflammatory indices to workplace exposure. Their diagnostic performances, alone and in combination, are critically reviewed and summarized into evidence-based key messages. A working diagnostic algorithm is proposed that can be adapted to the suspected agent, purpose of diagnosis, and available resources. Current information on the management options of OA is summarized to provide pragmatic guidance to clinicians who have to advise their patients with OA.

Identification of peroxidase-1 and beta-glucosidase as cross-reactive wheat allergens in grass pollen-related wheat allergy

BACKGROUND

Some patients with wheat-dependent exercise-induced anaphylaxis (WDEIA) or wheat allergy showed negative ω-5 gliadin-specific IgE test and high level of grass pollen-specific IgE. It was presumed that these patients developed allergic reaction upon cross-reaction of their IgE antibodies raised against grass pollen allergens to wheat allergens. This study aimed to clarify clinical characteristics and wheat allergens of this phenotype of WDEIA/wheat allergy, which were tentatively diagnosed as grass pollen-related wheat allergy (GPWA).

METHODS

A total of six patients with GPWA were enrolled, and controls were 17 patients with grass pollen allergy but no episode of wheat allergy, and 29 patients with other wheat allergies: 18 with conventional WDEIA and 11 with hydrolyzed wheat protein allergy. Sensitization to wheat proteins was determined by basophil activation test (BAT). IgE-binding proteins in wheat flour were identified by immunoblotting followed by mass spectrometry. Wheat allergen-specific IgE tests were established by CAP-FEIA system.

RESULTS

All the six patients with GPWA were sensitized to water-soluble wheat proteins in BAT and IgE-immunoblotting, and peroxidase-1 (35 kDa) and beta-glucosidase (60 kDa) were identified as specific IgE-binding wheat proteins. The binding of patient IgE to these proteins was inhibited by pre-incubation of patient sera with grass pollen. The peroxidase-1- and beta-glucosidase-specific IgE tests identified three and four of six patients with GPWA, respectively, but only two of 29 controls, indicating high specificity of these tests.

CONCLUSIONS

Peroxidase-1 and beta-glucosidase are specific wheat allergens for GPWA among grass pollen allergy and other types of wheat-induced food allergies.

Are Physicochemical Properties Shaping the Allergenic Potency of Plant Allergens?

This review searched for published evidence that could explain how different physicochemical properties impact on the allergenicity of food proteins and if their effects would follow specific patterns among distinct protein families. Owing to the amount and complexity of the collected information, this literature overview was divided in two articles, the current one dedicated to protein families of plant allergens and a second one focused on animal allergens. Our extensive analysis of the available literature revealed that physicochemical characteristics had consistent effects on protein allergenicity for allergens belonging to the same protein family. For example, protein aggregation contributes to increased allergenicity of 2S albumins, while for legumins and cereal prolamins, the same phenomenon leads to a reduction. Molecular stability, related to structural resistance to heat and proteolysis, was identified as the most common feature promoting plant protein allergenicity, although it fails to explain the potency of some unstable allergens (e.g. pollen-related food allergens). Furthermore, data on physicochemical characteristics translating into clinical effects are limited, mainly because most studies are focused on in vitro IgE binding. Clinical data assessing how these parameters affect the development and clinical manifestation of allergies is minimal, with only few reports evaluating the sensitising capacity of modified proteins (addressing different physicochemical properties) in murine allergy models. In vivo testing of modified pure proteins by SPT or DBPCFC is scarce. At this stage, a systematic approach to link the physicochemical properties with clinical plant allergenicity in real-life scenarios is still missing.

Progress in Occupational Asthma

Occupational asthma (OA) represents one of the major public health problems due to its high prevalence, important social and economic burden. The aim of this review is to summarize current data about clinical phenotypes, biomarkers, diagnosis and management of OA, a subtype of work-related asthma. Most studies have identified two phenotypes of OA. One is sensitizer-induced asthma, occuring after a latency period and caused by hypersensitivity to high- or low-molecular weight agents. The other is irritant-induced asthma, which can occur after one or more exposures to high concentrations of irritants without latency period. More than 400 agents causing OA have been identified and its list is growing fast. The best diagnostic approach for OA is a combination of clinical history and objective tests. An important tool is a specific inhalation challenge. Additional tests include assessments of bronchial hyperresponsiveness to methacholine/histamine in patients without airflow limitations, monitoring peak expiratory flow at- and off-work, sputum eosinophil count, exhaled nitric oxide measurement, skin prick tests with occupational allergens and serum specific IgE. Treatment of OA implies avoidance of exposure, pharmacotherapy and education. OA is a heterogeneous disease. Mechanisms of its different phenotypes, their diagnosis, role of new biomarkers and treatment require further investigation.

A WAO - ARIA - GA2LEN consensus document on molecular-based allergy diagnosis (PAMD@): Update 2020

Precision allergy molecular diagnostic applications (PAMD@) is increasingly entering routine care. Currently, more than 130 allergenic molecules from more than 50 allergy sources are commercially available for in vitro specific immunoglobulin E (sIgE) testing. Since the last publication of this consensus document, a great deal of new information has become available regarding this topic, with over 100 publications in the last year alone. It thus seems quite reasonable to publish an update. It is imperative that clinicians and immunologists specifically trained in allergology keep abreast of the new and rapidly evolving evidence available for PAMD@.

PAMD@ may initially appear complex to interpret; however, with increasing experience, the information gained provides relevant information for the allergist. This is especially true for food allergy, Hymenoptera allergy, and for the selection of allergen immunotherapy. Nevertheless, all sIgE tests, including PAMD@, should be evaluated within the framework of a patient's clinical history, because allergen sensitization does not necessarily imply clinical relevant allergies.

Immunological methods for diagnosis and monitoring of IgE-mediated allergy caused by industrial sensitizing agents (IMExAllergy)

Industrial sensitizing agents (allergens) in living and working environments play an important role in eliciting type 1 allergic disorders including asthma and allergic rhinitis. Successful management of allergic diseases necessitates identifying their specific causes (ie, identify the causative agent(s) and the route of contact to allergen: airborne, or skin contact) to avoid further exposure. Identification of sensitization by a sensitive and validated measurement of specific IgE is an important step in the diagnosis. However, only a limited number of environmental and occupational allergens are available on the market for use in sIgE testing. Accordingly, specific in‐house testing by individual diagnostic and laboratory centers is often required. Currently, different immunological tests are in use at various diagnostic centers that often produce considerably divergent results, mostly due to lack of standardized allergen preparation and standardized procedures as well as inadequate quality control. Our review and meta‐analysis exhibited satisfactory performance of sIgE detection test for most high molecular weight (HMW) allergens with a pooled sensitivity of 0.74 and specificity of 0.71. However, for low molecular weight (LMW) allergens, pooled sensitivity is generally lower (0.28) and specificity higher (0.89) than for HMW tests. Major recommendations based on the presented data include diagnostic use of sIgE to HMW allergens. A negative sIgE result for LMW agents does not exclude sensitization. In addition, the requirements for full transparency of the content of allergen preparations with details on standardization and quality control are underlined. Development of standard operating procedures for in‐house sIgE assays, and clinical validation, centralized quality control and audits are emphasized. There is also a need for specialized laboratories to provide a custom service for the development of tests for the measurement of putative novel occupational allergens that are not commercially available.

Food processing and occupational respiratory allergy- An EAACI position paper

Occupational exposure to foods is responsible for up to 25% of cases of occupational asthma and rhinitis. Animal and vegetable high-molecular-weight proteins present in aerosolized foods during food processing, additives, preservatives, antioxidants, and food contaminants are the main inhalant allergen sources. Most agents typically cause IgE-mediated allergic reactions, causing a distinct form of food allergy (Class 3 food allergy). The allergenicity of a food protein, allergen exposure levels, and atopy are important risk factors. Diagnosis relies on a thorough medical and occupational history, functional assessment, assessment of sensitization, including component-resolved diagnostics where appropriate, and in selected cases specific inhalation tests. Exposure assessment, including allergen determination, is a cornerstone for establishing preventive measures. Management includes allergen exposure avoidance or reduction (second best option), pharmacological treatment, assessment of impairment, and worker's compensation. Further studies are needed to identify and characterize major food allergens and define occupational exposure limits, evaluate the relative contribution of respiratory versus cutaneous sensitization to food antigens, evaluate the role of raw versus cooked food in influencing risk, and define the absolute or relative contraindication of patients with ingestion-related food allergy, pollinosis, or oral allergy syndrome continuing to work with exposure to aerosolized food allergens.

Performance of specific immunoglobulin E tests for diagnosing occupational asthma: a systematic review and meta-analysis

OBJECTIVES

To determine the test performance parameters for the retrievable range of high-molecular-weight (HMW) and low-molecular-weight (LMW) occupational allergens and to evaluate the impact of allergenic components and the implementation of measures for test validation.

METHODS

A protocol with predefined objectives and inclusion criteria was the basis of an electronic literature search of MEDLINE and EMBASE (time period 1967-2016). The specific inhalation challenge and serial peak flow measurements were the reference standards for the specific IgE (sIgE) test parameters. All of the review procedures were reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

RESULTS

Seventy-one studies were selected, and 62 entered meta-analysis. Pooled pairs analysis indicated a sensitivity of 0.74(95% CI 0.66 to 0.80) and specificity of 0.71(95% CI 0.63 to 0.77) for HMW allergens and a sensitivity of 0.28(95% CI 0.18 to 0.40) and specificity of 0.89(95% CI 0.77 to 0.95) for LMW allergens. Component-specific analysis improved the test parameters for some allergens. Test validation was handled heterogeneously among studies.

CONCLUSION

sIgE test performance is rather satisfactory for a wide range of HMW allergens with the potential for component-specific approaches, whereas sensitivity for LMW allergens is considerably lower, indicating methodological complications and/or divergent pathomechanisms. A common standard for test validation is needed.

Non-Celiac Gluten Sensitivity: A Challenging Diagnosis in Children with Abdominal Pain

Several disorders related to the ingestion of gluten are well recognized despite overlapping clinical presentations: celiac disease, an autoimmune enteropathy triggered by gluten ingestions in susceptible individuals, allergy to wheat, and more recently non-celiac gluten sensitivity (NCGS). While celiac disease and wheat allergy are well-known disorders with a clear-cut diagnosis based on clinical tests and biological parameters, NCGS is a more difficult diagnosis, especially in children with functional gastrointestinal (GI) complaints. NCGS is considered a syndrome of intestinal but also extraintestinal symptoms occurring within hours, but sometimes even after several days of gluten ingestion. In children, the leading symptoms of NCGS are abdominal pain and diarrhea, while extraintestinal symptoms are rare, in contrast to adult patients. No precise diagnostic test nor specific biomarkers exist, except a rather cumbersome three-phase gluten-exposure, gluten-free diet, followed by a blinded placebo-controlled gluten challenge with crossover to provoke symptoms elicited by gluten in a reproducible manner that disappear on gluten-free alimentation. Recent data indicate that the peptide part of wheat proteins is not necessarily the sole trigger of clinical symptoms. Mono- or oligosaccharides, such as fructan and other constituents of wheat, were able to provoke GI symptoms in clinical trials. These new findings indicate that the term gluten sensitivity is probably too restrictive. The incidence of NCGS was reported in the range of 1-10% in the general population and to increase steadily; however, most data are based on patients' self-reported gluten intolerance or avoidance without a medically confirmed diagnosis. Treatment consists of gluten avoidance for at least several weeks or months. Patients with NCGS require regular reassessment for gluten tolerance allowing with time the reintroduction of increasing amounts of gluten.

Identification and molecular characterization of allergenic non-specific lipid-transfer protein from durum wheat (Triticum turgidum)

BACKGROUND

Common wheat (Triticum aestivum) and durum wheat (T. turgidum) are both involved in Baker's asthma (BA) and food allergy (FA) including wheat-dependent exercise-induced asthma (WDEIA). However, allergens in durum wheat have not been described, and the over-expression of T. turgidum non-specific lipid-transfer protein (nsLTPs) is considered to increase resistance to phytopathogens.

OBJECTIVE

To identify and assess the allergenicity of nsLTP from T. turgidum.

METHODS

Recombinant T. turgidum nsLTP Tri tu 14 was generated and tested for structural integrity (circular dichroism-spectroscopy) and purity (SDS-PAGE). Thirty-two wheat allergic patients were enrolled: 20 Spanish patients (BA) with positive bronchial challenge to wheat flour, and 12 Italian patients (wheat FA/WDEIA) with positive double-blind placebo-controlled food challenge/open food challenge (OFC) to pasta. IgE values to wheat, Tri tu 14, Tri a 14 (T. aestivum) and Pru p 3 (P. persica) were determined by ImmunoCAP testing. Allergenic potency (in vitro mediator release) and IgE cross-reactivity were investigated.

RESULTS

Tri tu 14 was found to share 49% and 52% amino acid identity with Tri a 14 and Pru p 3, respectively. Among 25 Tri a 14 CAP positive sera, 23 (92%) were reactive to wheat extract, 22 (88%) to Tri tu 14 and 20 (80%) to Pru p 3. The correlation between Tri a 14 and Tri tu 14 specific IgE levels was r = 0.97 (BA) and r = 0.93 (FA/WDEIA), respectively. FA/WDEIA patients showed higher specific IgE values to Tri tu 14 and Pru p 3 than BA patients. Tri tu 14 displayed allergenic activity by mediator release from effector cells and IgE cross-reactivity with Pru p 3. The degree of IgE cross-reactivity between the two wheat nsLTPs varied between individual patients.

CONCLUSIONS AND CLINICAL RELEVANCE

Sensitization to Tri tu 14 likely appears to be more important in wheat FA/WDEIA than in BA. Over-expression of Tri tu 14 in wheat would represent a risk for patients with nsLTP-mediated FA.

Grass-Allergic Children Frequently Show Asymptomatic Low-Level IgE Co-Sensitization and Cross-Reactivity to Wheat

BACKGROUND

Specific immunoglobulin E (IgE) sensitization to wheat is more common than a doctor's confirmed wheat allergy and is also frequently observed in grass pollen-allergic patients (pollinosis patients). Thus, the objective of this study was to investigate the level and feature of serological IgE cross-reactivity between grass pollen and wheat in a cohort of pollinosis subjects with no diagnosis of wheat allergy.

METHODS

Seventy-two children, aged 5-17 years, with a doctor's diagnosis of pollinosis, IgE towards grass pollen, and currently eating wheat were recruited. Serum samples were analyzed for IgE against wheat, timothy grass/wheat-specific allergen components, Pru p 3, and cross-reactive carbohydrate determinants (CCD) and specific IgE-binding inhibition experiments were performed.

RESULTS

Sixty percent of the grass pollen subjects were sensitized to wheat with a median of 0.5 kUA/L. Wheat-sensitized subjects were more often sensitized to the two allergens, Phl p 12 and CCD, known to be cross-reactive between grass and wheat. Sensitizations to seven wheat-specific allergens derived from the gluten fraction were, with the exception of one individual, only found in wheat-sensitized subjects. These subjects also more often reported current and past history of allergy to staple foods (milk, egg, wheat, soy, and fish).

CONCLUSION

Wheat sensitization caused by cross-reactivity but also by sensitization to wheat-specific allergens was common in the grass-allergic children and also associated with allergy to staple foods other than wheat. The results indicate the presence of a subgroup of pollinosis patients with simultaneous sensitization to wheat and food allergy not only caused by cross-reactions.

An Official American Thoracic Society Workshop Report: Presentations and Discussion of the Sixth Jack Pepys Workshop on Asthma in the Workplace

The Sixth Jack Pepys Workshop on Asthma in the Workplace focused on six key themes regarding the recognition and assessment of work-related asthma and airway diseases: (1) cleaning agents and disinfectants (including in swimming pools) as irritants and sensitizers: how to evaluate types of bronchial reactions and reduce risks; (2) population-based studies of occupational obstructive diseases: use of databanks, advantages and pitfalls, what strategies to deal with biases and confounding?; (3) damp environments, dilapidated buildings, recycling processes, and molds, an increasing problem: mechanisms, how to assess causality and diagnosis; (4) diagnosis of occupational asthma and rhinitis: how useful are recombinant allergens (component-resolved diagnosis), metabolomics, and other new tests?; (5) how does exposure to gas, dust, and fumes enhance sensitization and asthma?; and (6) how to determine probability of occupational causality in chronic obstructive pulmonary disease: epidemiological and clinical, confirmation, and compensation aspects. A summary of the presentations and discussion is provided in this proceedings document. Increased knowledge has been gained in each topic over the past few years, but there remain aspects of controversy and uncertainty requiring further research.

Allergen component analysis as a tool in the diagnosis and management of occupational allergy

We are now in the epoch of "molecular allergology" and numerous clinically relevant allergenic molecules are available improving the performance of in vitro allergen tests and allergen detection methods. This review is focusing on characterized occupational allergens and their implementation into the in vitro diagnosis for occupational allergy and in allergen detection methods. More than 400 occupational agents are identified and documented as being 'respiratory sensitizers', but currently only a limited number of them are characterized on the molecular level and available for routine diagnosis as native or recombinant allergens. One exception, however, is natural rubber latex (NRL) from Hevea brasiliensis still remaining an important occupational allergen source. Characterization of 15 NRL allergens led to the development of assays for the determination of allergen content of NRL materials and the implementation of component-resolved diagnosis (CRD) for specific IgE antibody measurement. Microarray or singleplex using recombinant or native allergens are reliable tools for NRL allergy diagnosis. In addition, NRL allergy is an excellent model for improving extract-based specific IgE measurement by amplification of NRL extract preparation with stable recombinant major allergen rHev b 5. Despite the many efforts to characterize the occupationally relevant wheat allergens for baker's asthma, the most frequently occurring forms of occupational asthma, the results are highly diverse. Wheat sensitization profiles of bakers showed great interindividual variability and no wheat allergen could be classified as the major allergen. For diagnosis of baker's asthma, a whole wheat extract is still the best option for specific IgE determination. But single wheat allergens might help to discriminate between wheat-induced food allergy, grass pollen allergy and baker's asthma. For workplace-related allergens like coffee, wood, soybean, seafood and moulds allergens are characterized and few of them are available, but their relevance for occupational sensitization routes should be verified in the further studies.

Addressing Molecular Diagnosis of Occupational Allergies

PURPOSE OF REVIEW

Numerous clinically relevant allergenic molecules enhance the performance of specific (s) IgE tests and improve the specificity of allergy diagnosis. This review aimed to summarize our current knowledge of the high-molecular-weight allergens involved in the development of occupational asthma and rhinitis and to critically analyze the contribution of component-resolved diagnosis in the management of these conditions.

RECENT FINDINGS

There is a lack of standardization and validation for most available extracts of occupational agents, and assessment of sIgE reactivity to occupational allergen components has been poorly investigated, with the notable exception of natural rubber latex (NRL) and wheat flour. In the case of NRL, the application of recombinant single allergens and amplification of natural extracts with stable recombinant allergens improved the test sensitivity. IgE-sensitization profile in patients with baker's asthma showed great interindividual variation, and extract-based diagnostic is still recommended. For other occupational allergens, it remains necessary to evaluate the relevance of single allergen molecules for the sensitization induced by occupational exposure. Progress has been made to characterize occupational allergens especially NRL and wheat, although there is still an unmet need to increase the knowledge of occupational allergens, to include standardized tools into routine diagnostic, and to evaluate their usefulness in clinical practice.

Diagnosing occupational asthma

Making an accurate diagnosis of occupational asthma (OA) is, generally, important. The condition has not only significant health consequences for affected workers, but also substantial socio-economic impacts for workers, their employers and wider society. Missing a diagnosis of OA may lead to continued exposure to a causative agent and progressive worsening of disease; conversely, diagnosing OA when it is not present may lead to inappropriate removal from exposure and unnecessary financial and social consequences. While the most accurate investigation is specific inhalation challenge in an experienced centre, this is a scarce resource, and in many cases, reliance is on other tests. This review provides a technical dossier of the diagnostic value of the available methods which include an appropriate clinical history, the use of specific immunology and measurement of inflammatory markers, and various methods of relating functional changes in airway calibre to periods at work. It is recommended that these approaches are used iteratively and in judicious combination, in cognizance of the individual patient's circumstances and requirements. Based on available evidence, a working diagnostic algorithm is proposed that can be adapted to the suspected agent, purpose of diagnosis and available resources. For better or worse, many of the techniques - and their interpretation - are available only in specialized centres and where there is room for doubt, referral to such a centre is probably wise. Accordingly, the implementation or development of such specialized centres with appropriate equipment and expertise should greatly improve the diagnostic evaluation of work-related asthma.

Comparing immediate-type food allergy in humans and companion animals-revealing unmet needs

Adverse food reactions occur in human as well as veterinary patients. Systematic comparison may lead to improved recommendations for prevention and treatment in both. In this position paper, we summarize the current knowledge on immediate-type food allergy vs other food adverse reactions in companion animals, and compare this to the human situation. While the prevalence of food allergy in humans has been well studied for some allergens, this remains to be investigated for animal patients, where owner-reported as well as veterinarian-diagnosed food adverse reactions are on the increase. The characteristics of the disease in humans vs dogs, cats, and horses are most often caused by similar, but sometimes species-dependent different pathophysiological mechanisms, prompting the specific clinical symptoms, diagnoses, and treatments. Furthermore, little is known about the allergen molecules causative for type I food allergy in animals, which, like in human patients, could represent predictive biomarkers for risk evaluation. The definite diagnosis of food allergy relies-as in humans-on elimination diet and provocation tests. Besides allergen avoidance in daily practice, novel treatment options and tolerization strategies are underway. Taken together, numerous knowledge gaps were identified in veterinary food allergy, which need to be filled by systematic comparative studies.

Food allergy and the gut

Food allergy develops as a consequence of a failure in oral tolerance, which is a default immune response by the gut-associated lymphoid tissues to ingested antigens that is modified by the gut microbiota. Food allergy is classified on the basis of the involvement of IgE antibodies in allergic pathophysiology, either as classic IgE, mixed pathophysiology or non-IgE-mediated food allergy. Gastrointestinal manifestations of food allergy include emesis, nausea, diarrhoea, abdominal pain, dysphagia, food impaction, protein-losing enteropathy and failure to thrive. Childhood food allergy has a generally favourable prognosis, whereas natural history in adults is not as well known. Elimination of the offending foods from the diet is the current standard of care; however, future therapies focus on gradual reintroduction of foods via oral, sublingual or epicutaneous food immunotherapy. Vaccines, modified hypoallergenic foods and modification of the gut microbiota represent additional approaches to treatment of food allergy.

Occupational Allergies: A Brief Review

Occupational allergies are groups of work-related disorders that are accompanied by immunologic reaction to workplace allergens and include occupational asthma, rhinitis, hypersensitivity pneumonitis, dermatitis, and anaphylaxis. This mini review presents a brief analysis of the more important aspects of occupational allergic disorders.

Allergen component analysis as a tool in the diagnosis of occupational allergy

PURPOSE OF REVIEW

Rapid developments have been seen in molecular allergy diagnosis, based on the detection and quantification of specific IgE to single allergens. This review summarizes and discusses studies on allergen component analysis as a tool in the diagnosis of occupational allergy.

RECENT FINDINGS

More than 400 agents are identified as sensitizers of occupational asthma, but only very few are characterized on the molecular level and available for routine diagnosis. Baker's asthma is one of the most frequently occurring forms of occupational asthma caused by workplace-related inhalation of cereal flour mainly wheat. Wheat sensitization profiles of bakers show great interindividual variability and no wheat allergen could be classified as the major allergen. Component-resolved diagnosis is a useful tool for diagnosing natural rubber latex (NRL) allergy. In cases with unexpected high-latex IgE but without clinical symptoms application of crossreactive carbohydrate determinants are helpful to clarify the cause of IgE binding.

SUMMARY

Latex is an excellent model for component-resolved diagnosis and demonstrates well how to improve the diagnosis by using single allergens. For diagnosis of baker's asthma, a whole wheat extract is still the best option for specific IgE determination, but single wheat allergens might help to discriminate between wheat-induced food allergy, grass-pollen allergy, and baker's asthma. New diagnostic tools and platforms are promising, but further knowledge of molecules relevant for occupational asthma (as in wood dust allergens, enzymes, laboratory animal allergens, etc.) and for occupational hypersensitivity pneumonitis is necessary to improve and standardize the diagnostic tools.

New developments in work-related asthma

INTRODUCTION

Work-related asthma includes two subtypes: occupational asthma or asthma caused by specific agents (sensitizers or irritants) in the workplace, and work-exacerbated asthma or pre-existing asthma worsened by workplace exposures. Areas covered: This review provides an update on the definitions and the clinical features of the different work-related asthma subtypes as well as new insights into their etiology and the pathophysiological mechanisms involved. The diagnosis of work-related asthma should be made on objective basis using a constellation of clinical, physiologic and allergologic tests. Specific inhalation challenge with the suspected occupational agent(s) remains as the reference standard for diagnosis. A literature search was performed using the following terms: work-related asthma, occupational asthma, work-exacerbated asthma, irritant-induced asthma and etiological agents. Expert commentary: Studies focusing on the biological effects and mechanisms of environmental exposures in the development of sensitizer-induced or irritant-induced asthma in various workplace settings are of greatest interest. An integrative approach that combines clinical parameters with component-resolved diagnosis as well as inflammatory biomarkers appears to be very promising. Occupational allergy provides a good opportunity to understand the complex relationships between exposure to allergens in the workplace, interaction with genes and the co-exposures to other factors in the working environment.

Very low prevalence of IgE mediated wheat allergy and high levels of cross-sensitisation between grass and wheat in a UK birth cohort

Background

Patients often report adverse reactions to wheat. Interpretation of sensitization to wheat pollen and flour with/without sensitization to grass pollen is a clinical problem.

Aim

We set out to determine the prevalence of wheat allergy in a birth cohort (10/11 year olds) and investigate the usefulness of performing skin prick tests (SPT), specific IgE tests and component resolved diagnostics to wheat pollen and flour.

Methods

The Food Allergy and Intolerance Research (FAIR) birth cohort included babies born on the Isle of Wight (UK) between September 2001–August 2002 (n = 969). Children were followed up at 1, 2, 3 and 10/11 years. 588 children had SPTs to wheat pollen and grass during the 10 year follow-up. 294 children underwent further SPT to wheat flour and 246 had specific IgE testing to wheat and grass.

Results

Eight children underwent oral food challenges (OFC). We diagnosed 0.48 % (4/827; 95 % CI 0–1 %) children with wheat allergy based on OFC. 16.3 % (96/588) were sensitized to grass pollen, 13.4 % (79/588) to wheat pollen; 78 % (75/96) sensitized to both. Only one child was sensitized to wheat flour and wheat pollen, but not grass pollen. For specific IgE, 15.0 % (37/246) and 36.2 % (89/246) were sensitized to wheat and grass pollen, with 40.5 % (36/89) sensitized to both. Of the 37 children sensitized to wheat, 3 (8.1 %) were sensitized to omega 5 gliadin, 1 (2.7 %) to wheat lipid transfer protein and 1 to wheat gliadin.

Conclusion

Clinicians should be aware of the high level of cross-sensitization when performing tests to wheat and grass pollen i.e. sensitisation to wheat specific IgE and wheat pollen SPT should be assessed in the presence of grass pollen SPT and/or specific IgE.

Potential of molecular based diagnostics and its impact on allergen immunotherapy

Molecular based in vitro technologies greatly changed the diagnostic approaches in allergy. At present, sensitization profiles can be dissected according to IgE subsets, which are specific for genuine or cross-reacting components and potentially dangerous or virtually harmless components. The identification of IgE in components with specific characteristics has a direct impact on the accuracy of the diagnosis (indeed, it is possible at present to not only identify the allergen derived from a given allergen source but also the family of molecules to which the patient is sensitized), on the prognosis of the patient’s allergy, and on the prevention activities to be implemented. More interestingly, during the last few years, and thanks to the tools of molecular diagnostics, the indications for Allergen Immunotherapy (AIT) have also be modified, and novel strategies for the selection of the allergens to be administered have been better defined. Indeed, protocols indicating how Molecular Based Diagnosis (MBD) can be used to identify the best AIT approach have been recently published. In this review, the rationale for the use of MBD tools is discussed, and the recent strategies for the choice of allergens to be used in AIT are reported.

Triticale allergy in a farmer

We present the case of a 29-year-old farmer with hay fever and atopic dermatitis since adolescence who had developed work-related asthma about 5 years earlier. He was sensitized to grass pollen, wheat and rye flour, dust from the floors of the animal facilities (cows and pigs) and grain barn, and a battery of animal feed from his farm. Work-relatedness of his asthma was demonstrated by serial measurements of spirometry and fractional exhaled nitric oxide at work and during a holiday. Immunoblot analyses revealed dominant IgE-binding to grass pollen and triticale (a hybrid of rye and wheat). IgE inhibition experiments demonstrated that sensitization to triticale was not due to cross-reactivity to grass pollen. Testing of specific IgE-antibodies to recombinant wheat allergens showed sensitizations to profilin, peroxidase, and nonspecific lipid transfer proteins type I subfamily 9.1 and 9.7. We conclude that triticale allergy may occur as a distinct allergy in farmers. Am. J. Ind. Med. 59:501-505, 2016. © 2016 Wiley Periodicals, Inc.

EAACI Molecular Allergology User's Guide

The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients.

Clinical presentation, allergens, and management of wheat allergy

IgE-mediated allergy to wheat proteins can be caused by exposure through ingestion, inhalation, or skin/mucosal contact, and can affect various populations and age groups. Respiratory allergy to wheat proteins is commonly observed in adult patients occupationally exposed to flour, whereas wheat food allergy is more common in children. Wheat allergy is of growing importance for patients with recurrent anaphylaxis, especially when exercise related. The diagnosis of wheat allergy relies on a consistent clinical history, skin prick testing with well-characterized extracts and specific IgE tests. The accuracy of wheat allergy diagnosis may be improved by measuring IgE responses to several wheat components. However, a high degree of heterogeneity has been found in the recognition pattern of allergens among patient groups with different clinical profiles, as well as within each group. Thus, oral provocation with wheat or the implicated cereal is the reference test for the definitive diagnosis of ingested wheat/cereal allergy.

Wheat allergy: diagnosis and management

Triticum aestivum (bread wheat) is the most widely grown crop worldwide. In genetically predisposed individuals, wheat can cause specific immune responses. A food allergy to wheat is characterized by T helper type 2 activation which can result in immunoglobulin E (IgE) and non-IgE mediated reactions. IgE mediated reactions are immediate, are characterized by the presence of wheat-specific IgE antibodies, and can be life-threatening. Non-IgE mediated reactions are characterized by chronic eosinophilic and lymphocytic infiltration of the gastrointestinal tract. IgE mediated responses to wheat can be related to wheat ingestion (food allergy) or wheat inhalation (respiratory allergy). A food allergy to wheat is more common in children and can be associated with a severe reaction such as anaphylaxis and wheat-dependent, exercise-induced anaphylaxis. An inhalation induced IgE mediated wheat allergy can cause baker’s asthma or rhinitis, which are common occupational diseases in workers who have significant repetitive exposure to wheat flour, such as bakers. Non-IgE mediated food allergy reactions to wheat are mainly eosinophilic esophagitis (EoE) or eosinophilic gastritis (EG), which are both characterized by chronic eosinophilic inflammation. EG is a systemic disease, and is associated with severe inflammation that requires oral steroids to resolve. EoE is a less severe disease, which can lead to complications in feeding intolerance and fibrosis. In both EoE and EG, wheat allergy diagnosis is based on both an elimination diet preceded by a tissue biopsy obtained by esophagogastroduodenoscopy in order to show the effectiveness of the diet. Diagnosis of IgE mediated wheat allergy is based on the medical history, the detection of specific IgE to wheat, and oral food challenges. Currently, the main treatment of a wheat allergy is based on avoidance of wheat altogether. However, in the near future immunotherapy may represent a valid way to treat IgE mediated reactions to wheat.

Common food allergens and their IgE-binding epitopes

Food allergy is an adverse immune response to certain kinds of food. Although any food can cause allergic reactions, chicken egg, cow's milk, wheat, shellfish, fruit, and buckwheat account for 75% of food allergies in Japan. Allergen-specific immunoglobulin E (IgE) antibodies play a pivotal role in the development of food allergy. Recent advances in molecular biological techniques have enabled the efficient analysis of food allergens. As a result, many food allergens have been identified, and their molecular structure and IgE-binding epitopes have also been identified. Studies of allergens have demonstrated that IgE antibodies specific to allergen components and/or the peptide epitopes are good indicators for the identification of patients with food allergy, prediction of clinical severity and development of tolerance. In this review, we summarize our current knowledge regarding the allergens and IgE epitopes in the well-researched allergies to chicken egg, cow's milk, wheat, shrimp, and peanut.