Applications of Molecular Diagnostic Testing in Food Allergy

Allergy-associated biomarkers in early life identified by Omics techniques

The prevalence and severity of allergic diseases have increased over the last 30 years. Understanding the mechanisms responsible for these diseases is a major challenge in current allergology, as it is crucial for the transition towards precision medicine, which encompasses predictive, preventive, and personalized strategies. The urge to identify predictive biomarkers of allergy at early stages of life is crucial, especially in the context of major allergic diseases such as food allergy and atopic dermatitis. Identifying these biomarkers could enhance our understanding of the immature immune responses, improve allergy handling at early ages and pave the way for preventive and therapeutic approaches. This minireview aims to explore the relevance of three biomarker categories (proteome, microbiome, and metabolome) in early life. First, levels of some proteins emerge as potential indicators of mucosal health and metabolic status in certain allergic diseases. Second, bacterial taxonomy provides insight into the composition of the microbiota through high-throughput sequencing methods. Finally, metabolites, representing the end products of bacterial and host metabolic activity, serve as early indicators of changes in microbiota and host metabolism. This information could help to develop an extensive identification of biomarkers in AD and FA and their potential in translational personalized medicine in early life.

IgE-Mediated food allergy: Current diagnostic modalities and novel biomarkers with robust potential

Food allergy (FA) is a serious public health issue afflicting millions of people globally, with an estimated prevalence ranging from 1-10%. Management of FA is challenging due to overly restrictive diets and the lack of diagnostic approaches with high accuracy and prediction. Although measurement of serum-specific antibodies combined with patient medical history and skin prick test is a useful diagnostic tool, it is still an imprecise predictor of clinical reactivity with a high false-positive rate. The double-blind placebo-controlled food challenge represents the gold standard for FA diagnosis; however, it requires large healthcare and involves the risk of acute onset of allergic reactions. Improvement in our understanding of the molecular mechanism underlying allergic disease pathology, development of omics-based methods, and advances in bioinformatics have boosted the generation of a number of robust diagnostic biomarkers of FA. In this review, we discuss how traditional diagnostic modalities guide appropriate diagnosis and management of FA in clinical practice, as well as uncover the potential of the latest biomarkers for the diagnosis, monitoring, and prediction of FA. We also raise perspectives for precise and targeted medical intervention to fill the gap in the diagnosis of FA.

The effect of immunotherapy on cross-reactivity between house dust mite and other allergens in house dust mite -sensitized patients with allergic rhinitis

INTRODUCTION

House dust mite (HDM) is a main perennial allergen causing allergic rhinitis (AR). It has been shown that HDM cross-reacts with a variety of other allergens. Presently, allergen-specific immunotherapy (AIT) is an effective way for management of mono-sensitized HDM⁺ AR patients. However, management approaches to polysensitized HDM-sensitized AR patients are not standardized yet.

AREA COVERED

This article reviews the data available in the literature for cross-reactivity between HDM and inhalant or food allergens, the diagnosis of cross-reactivity in HDM-sensitized AR patients, and the effect of immunotherapy on cross-reactivity in HDM-sensitized AR patients; which may help to develop effective therapeutic strategies for management of polysensitized HDM-sensitized AR patients in the future.

EXPERT OPINION

Pan-allergen proteins such as tropomyosin, arginine kinase (AK), glutathione S-transferase (GST), and hemocyanin are responsible for cross-reactivity between HDM and other allergens. To distinguish genuine or cross-reactive sensitization, molecular- or component-resolved diagnosis is suggested to apply in HDM-sensitized AR patients. The effect of HDM immunotherapy to treat the associated cross-reactivity in HDM-sensitized AR patients is still contradictory, and might be dependent on the degree of homology between two allergens. Furthermore, targeting tropomyosin might be a promising way to treat HDM patients with allergen cross-reactivity.

ABBREVIATIONS

AIT: allergen-specific immunotherapy; AK: arginine kinase; AR: allergic rhinitis; CRD: component-resolved diagnostics; Der f: Dermatophagoides farina; Der p: Dermatophagoides pteronyssinus; EAACI: European Academy of Allergy and Clinical Immunology; GST: glutathione S-transferase; GWAS: genome-wide association study; HDM: house dust mite; IgE: immunoglobulin E; RAST: radioallergosorbent test; sIgE: specific IgE; SIT: specific immunotherapy; SCIT: subcutaneous immunotherapy; SLIT: sublingual immunotherapy; SPT: skin prick test.

Allergens and their associated small molecule ligands-their dual role in sensitization

Many allergens feature hydrophobic cavities that allow the binding of primarily hydrophobic small‐molecule ligands. Ligand‐binding specificities can be strict or promiscuous. Serum albumins from mammals and birds can assume multiple conformations that facilitate the binding of a broad spectrum of compounds. Pollen and plant food allergens of the family 10 of pathogenesis‐related proteins bind a variety of small molecules such as glycosylated flavonoid derivatives, flavonoids, cytokinins, and steroids in vitro. However, their natural ligand binding was reported to be highly specific. Insect and mammalian lipocalins transport odorants, pheromones, catecholamines, and fatty acids with a similar level of specificity, while the food allergen β‐lactoglobulin from cow's milk is notably more promiscuous. Non‐specific lipid transfer proteins from pollen and plant foods bind a wide variety of lipids, from phospholipids to fatty acids, as well as sterols and prostaglandin B2, aided by the high plasticity and flexibility displayed by their lipid‐binding cavities. Ligands increase the stability of allergens to thermal and/or proteolytic degradation. They can also act as immunomodulatory agents that favor a Th2 polarization. In summary, ligand‐binding allergens expose the immune system to a variety of biologically active compounds whose impact on the sensitization process has not been well studied thus far.

Peanut allergy diagnosis: Moving from basic to more elegant testing

Peanut allergy (PNA) is an IgE-mediated immune disorder, which merits particular attention due to its impact on the health and quality of life of millions of patients worldwide. PNA tends to develop in early life and resolves in only 20% of peanut-allergic children. It accounts for the majority of severe food-related allergic reactions. An accurate diagnosis of PNA is vital. In this review, we present the approach to the diagnosis of peanut allergy, starting from the history and proceeding to measures of overall sensitization and then to component-resolved diagnostics and oral food challenges as indicated. Additional testing in development includes basophil activation testing and determination of epitopes for peanut-allergic responses. Based on the literature, stepwise approaches and predictive models for diagnosing PNA are also presented.

IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper

Currently, testing for immunoglobulin E (IgE) sensitization is the cornerstone of diagnostic evaluation in suspected allergic conditions. This review provides a thorough and updated critical appraisal of the most frequently used diagnostic tests, both in vivo and in vitro. It discusses skin tests, challenges, and serological and cellular in vitro tests, and provides an overview of indications, advantages and disadvantages of each in conditions such as respiratory, food, venom, drug, and occupational allergy. Skin prick testing remains the first line approach in most instances; the added value of serum specific IgE to whole allergen extracts or components, as well as the role of basophil activation tests, is evaluated. Unproven, non-validated, diagnostic tests are also discussed. Throughout the review, the reader must bear in mind the relevance of differentiating between sensitization and allergy; the latter entails not only allergic sensitization, but also clinically relevant symptoms triggered by the culprit allergen.

Food Allergy Testing

Although the gold standard for diagnosis of immunoglobulin E (IgE)-mediated food allergy is an oral food challenge, clinically relevant biomarkers of IgE sensitization, including serum-specific IgE and skin prick testing, can aid in diagnosis. Clinically useful values have been defined for individual foods. More recently, specific IgE to particular protein components has provided additional diagnostic value. In summary, food allergy diagnostics to evaluate IgE sensitization are clinically useful and continue to evolve to improve evaluation of IgE-mediated food allergies.

Furry Animal Allergen Component Sensitization and Clinical Outcomes in Adult Asthma and Rhinitis

BACKGROUND

Sensitization to allergen components has been linked to asthma in children, but studies in adults are lacking.

OBJECTIVE

To study the relation of sensitization to furry animal allergen components to risk of asthma, rhinitis, and markers of asthma severity in adults.

METHODS

From the West Sweden Asthma Study, a random population-representative sample of adults aged 16 to 75 years, 2006 participants were clinically examined; 1872 were analyzed for serum IgE level to a mix of aeroallergens. Those with an IgE level of more than 0.35 kUA/L to cat, dog, or horse allergen components were analyzed for specific cat (Felis domesticus [Fel d 1, Fel d 2, and Fel d 4]), dog (Canis familiaris [Can f 1, Can f 2, Can f 3, and Can f 5]), and horse (Equus caballus [Equ c 1]) allergen components. We defined monosensitization, double sensitization, and polysensitization (>2 components) patterns and applied cluster analysis to derive distinct sensitization clusters.

RESULTS

Sensitization to each allergen component, lipocalins, each sensitization pattern, and each sensitization cluster (nonsensitized, Fel d 1-driven sensitized, and multisensitized clusters) was associated with substantial increased risk of asthma, rhinitis, concomitant asthma and rhinitis, and Asthma Control Test-controlled asthma. Fel d 1, Can f 1, Can f 2, Can f 3, polysensitization, and multisensitized cluster were further associated with increased fractional exhaled nitric oxide and eosinophil levels, but with lower PD20 methacoline (provocative dose of methacholine causing a 20% drop in FEV1) values. There was no association with asthma exacerbations, FEV1 predicted values, emergency visits or regular oral steroid use, and neutrophil levels.

CONCLUSIONS

Sensitization to furry animal allergen components is an important predictor of asthma, rhinitis, and markers of asthma severity with increased blood eosinophils, fractional exhaled nitric oxide, and airway hyperreactivity.

POLLEN–FOOD ALLERGY SYNDROME AMONG CHILDREN WITH SENSITIZED TO SPRING TREES

It is known that among 40–70 % of patients pollinosis can run in conjunction with pollen-food allergy syndrome (PFS), while development of PFS is associated with the consumption of fresh fruits, vegetables, nuts and spices. Clinical course and severity of the disease depend on the sensitization profile, which can be represented by proteins-panallergens (PR-10, profilins, nsLTPs). However, there is little information about the sensitization profiles of patients with pollinosis caused by pollen of spring trees in Ukraine. Aim. To study the profiles of sensitization of children with spring pollinosis. Methods. We examined 61 children (aged 4-17 years) with spring seasonal allergic rhinitis/rhinoconjunctivitis (SAR). To establish the diagnosis, all children were given questionnaires, skin prick tests (SPTs) with commercial pollen extracts, and prick to prick tests with fresh fruits, vegetables and nuts. Component resolved diagnosis (CRD) were detected using an ImmunoCAP system. (Phadia, 100). Results. It has been found that in 43 children (70.5 %) had polinosis in combination with PFS, the main clinical manifestation of which was an oral allergic syndrome in 43 children (100 %). Among the causal food allergens that caused the manifestations of PFS were more apples, peaches, carrots and hazelnuts (consumption of which led to 11.6 % of children before the development of anaphylaxis). All of the examined children (100 %) had a positive IgE response to rBet v 1 at significant concentrations. In 9.3 % of children, panallergens were found at once from several botanical groups. Such panallergens: rBet v 2, rBet v 4, rPhl p 7, rPhl p 12, rArt v 3 are generally not defined in the control group children. Conclusions. Birch related PFS are common in Ukrainian pollen-allergic children with nuts and fruits predominantly implicated. Sensitization profile of children with Birch-pollen syndrome is complex and associated with sensitization to panalergens. Clinicians should be worried of PFS in patients with a high degree of sensitization to birch pollen and even young children if they have birch sensitization.

Characterization of sensitization to furry animal allergen components in an adult population

BACKGROUND

There are paucity of data on sensitization to furry animal allergen components in adults. Furry animals are major sensitizers and contributors to asthma burden in northern Europe and North America.

OBJECTIVE

To characterize sensitization patterns to furry animal allergen components in Swedish adults.

METHODS

Based on the West Sweden Asthma Study, a random population (n = 1103) and an asthma sample (n = 769) were tested for allergen sensitization using Phadiatop^® . Those with IgE ≥ 0.35 kU_A /L were tested for cat (Fel d 1, 2, and 4), dog (Can f 1, 2, 3, and 5), and horse (Equ c 1) allergen component sensitization. We defined allergen component poly-sensitization patterns, identified data-driven sensitization clusters, described component sensitization overlaps, and assessed determinants of sensitization patterns.

RESULTS

The prevalence of allergen component sensitization ranged from 0.8% for Fel d 2 and Can f 3 to 8.9% for Fel d 1. The most common dog component was Can f 5 (3.6%); 2.1% were sensitized to Equ c 1. Those sensitized to Fel d 2 and Fel d 4 were commonly sensitized to Fel d 1. The most common dog component overlap was between Can f 1/Can f 2 and Can f 5. Mono-sensitization was 5.6%, double sensitization 1.5% and poly-sensitization 2.1%. Sensitization was always higher in the asthma than in the random sample. Three sensitization clusters were derived, namely non-sensitized (90% in random vs 66% in asthma sample); Fel d 1-driven sensitized (7% vs 19%); and multi-sensitized (3% vs 15%). Key determinants of sensitization were gender, age, raised on a farm, family history of allergy or asthma, smoking, and occupational exposure to dust or fumes.

CONCLUSIONS & CLINICAL RELEVANCE

Fel d 1 and Can f 5 are the most common cat and dog components sensitization in this adult Swedish population. Mono-sensitization is more common than poly-sensitization. This detailed characterization highlights the current distribution of furry animal allergen components in Swedish adults, and their impact on clinical outcomes of asthma will be further explored.

Molecular diagnostics improves diagnosis and treatment of respiratory allergy and food allergy with economic optimization and cost saving

BACKGROUND

Component resolved diagnosis (CRD) allows to precisely identify the sensitization to specific molecules of a given allergenic source, resulting in an important improvement in clinical management, particularly of polysensitized subjects. This will end in the correct prescription of allergen immunotherapy (AIT) for respiratory allergy and in adequate avoidance diets or prescription of self-injectable adrenaline in food allergy.

OBJECTIVE

The aim of this multicenter, real life study is to evaluate the percentage change of the diagnostic-therapeutic choice in polysensitized patients with respiratory allergy and in patients with food allergy, after using CRD compared to a first level diagnosis, along with an economic analysis of the patient's overall management according to the two different approaches.

METHODS

An overall number of 462 polysensitized patients, as suggested by skin prick tests (SPT), and with clinical symptoms related to a respiratory (275 pts) or food (187 pts) allergy, were recruited. All patients underwent CRD for specific IgE against food or inhalant recombinant molecules, which were chosen according to medical history and positivity to SPT. The first diagnostic-therapeutic hypothesis, based only on medical history and SPT, was recorded for each patient while the final diagnostic-therapeutic choice was based on the results from CRD. The rate of change of the diagnostic-therapeutic choice from the first hypothesis to the final choice was statistically evaluated. The economic impact of CRD on the overall management of the allergic patients was analyzed to evaluate whether the increase in the diagnostic costs would be compensated and eventually exceeded by savings coming from the improved diagnostic-therapeutic appropriateness.

RESULTS

An approximate 50% change (k index 0.54) in the prescription of AIT for respiratory allergy as well as a change in the prescription of self-injectable adrenaline (k index 0.56) was measured; an overall saving of financial resources along with a higher diagnostic-therapeutic appropriateness was also detected.

CONCLUSION

There is moderate agreement concerning prescription of AIT and self-injectable adrenaline before and after performing CRD: this highlights the usefulness of CRD, at least in polysensitized patients, in indicating the risk assessment and therefore the correct therapy of respiratory and food allergy, which results in a cost-saving approach.

Comparison of allergen-specific IgE levels between Immulite 2000 and ImmunoCAP systems against six inhalant allergens and ten food allergens

In vitro allergen-specific immunoglobulin E (sIgE) measurement has been used as an important diagnostic tool for allergic diseases. Currently, quantitative sIgE levels are detected mainly by using ImmunoCAP and Immulite 2000 assay system. These two systems have the same calibration scale at 0-100 kUA/L, but they differ in used allergens, detection methods and automation systems. We compared 1600 paired sIgE results for 204 allergic patients, including 100 paired sIgE assay results for each of 16 allergens (Alternaria alternata, birch-alder mix, cat dander, D. farinae, D. pteronyssinus, dog dander, buckwheat, crab, egg white, mackerel, milk, peach, peanut, shrimp, soybean and wheat flour). Inter-method comparison was performed for qualitative data with a cutoff of 0.35 kUA/L and a detection limit of 0.1 kUA/L, semi-quantitative class results and quantitative data. In qualitative comparisons, the overall concordance rate ranged from 81.0% to 99.0% (k: 0.599-0.949) with the cutoff value of 0.35 kUA/L. It also ranged from 80.0% to 99.0% (k: 0.521-0.951) with the detection limit of 0.1 kUA/L. The class results from these two assays showed good agreements for all allergens. For quantitative sIgE results, these two assays showed moderate positive correlations for Dog dander (r = 0.683) and Mackerel (r = 0.573) but high to very high correlations for the other 14 allergens (r = 0.734-0.972). Immulite 2000 and ImmunoCAP assays demonstrated good concordance and correlation for 16 common allergens, but international standards against each specific allergen for calibration and harmonization of sIgE tests are still needed.

Diagnostic accuracy, risk assessment, and cost-effectiveness of component-resolved diagnostics for food allergy: A systematic review

BACKGROUND

Component-resolved diagnostics (CRD) are promising tools for diagnosing food allergy, offering the potential to determine specific phenotypes and to develop patient-tailored risk profiles. Nevertheless, the diagnostic accuracy of these tests varies across studies; thus, their clinical utility remains unclear. Therefore, we synthesized the evidence from studies investigating the diagnostic accuracy, risk assessment ability, and cost-effectiveness of CRD for food allergy.

METHODS

We systematically searched 10 electronic databases and four clinical trial registries for studies published from January 2000 to February 2017. The quality of included studies was assessed using QUADAS-2. Due to heterogeneity, we narratively synthesized the evidence.

RESULTS

Eleven studies met inclusion criteria, altogether recruiting 1098 participants. The food allergies investigated were cow's milk, hen's egg, peanut, hazelnut, and shrimp. The components with the highest diagnostic accuracy for each allergen, along with their sensitivity-specificity pairs, were as follows: Bos d 4 for cow's milk (62.0% and 87.5%), Gal d 1 for hen's egg (84.2% and 89.8% for heated egg, and 60.6% and 97.1% for raw egg), Ara h 6 for peanut (94.9% and 95.1%), Cor a 14 for hazelnut (100% and 93.8%), and Lit v 1 for shrimp (82.8% and 56.3%) allergy.

CONCLUSION

Selected components of cow's milk, hen's egg, peanut, hazelnut, and shrimp allergen showed high specificity, but lower sensitivity. However, few studies exist for each component, and studies vary widely regarding the cutoff values used, making it challenging to synthesize findings across studies. Further research is needed to determine clinically appropriate cutoff values, risk assessment abilities, and cost-effectiveness of CRD approaches.

Component resolved diagnostic study of cow's milk allergy in infants and young children in northern China

BACKGROUND

Increasing dairy consumption in China has been accompanied by rising incidence of milk allergy. Here we analyzed profiles of specific immunoglobulin E (sIgE) against cow's milk proteins, and assessed their value for milk allergy diagnosis among infants and young children from northern China.

METHODS

Sera collected from 48 patients with milk allergy and 27 negative control subjects was analyzed by enzyme-linked immunosorbent assay to measure sIgE to α-lactalbumin (Bos d 4), β-lactoglobulin (Bos d 5), α-casein (Bos d 9), β-casein (Bos d 11), and κ-casein (Bos d 12).

RESULTS

Among milk-allergic individuals, most were sensitized to at least one milk protein; about half were sensitized to Bos d 5, Bos d 9, Bos d 11 and Bos d 12, respectively, while few had positive serum sIgE against Bos d 4. Bos d 12 sIgE had the largest area under curve (AUC) (0.878; 95% CI, 0.800-0.957) and thus showed the best diagnostic performance in discriminating between milk-allergic and non-milk allergic patients, with a sensitivity of 92.6% and specificity of 72.9% using a statistically optimal cut-off value (OD_450nm, 0.191). The combinations of Bos d 5 + Bos d 12 showed an AUC of 0.926, which was larger than for any individual components.

CONCLUSIONS

Our results revealed inter-individual variation in the sensitization to different milk allergen component. Bos d 12 sIgE showed best performance in diagnosing milk allergy. Milk allergy diagnostic accuracy was further improved using combinations of milk allergen components by application of ROC curves based on logistic regression.

A leukocyte activation test identifies food items which induce release of DNA by innate immune peripheral blood leucocytes

Background

Leukocyte activation (LA) testing identifies food items that induce a patient specific cellular response in the immune system, and has recently been shown in a randomized double blinded prospective study to reduce symptoms in patients with irritable bowel syndrome (IBS). We hypothesized that test reactivity to particular food items, and the systemic immune response initiated by these food items, is due to the release of cellular DNA from blood immune cells.

Methods

We tested this by quantifying total DNA concentration in the cellular supernatant of immune cells exposed to positive and negative foods from 20 healthy volunteers. To establish if the DNA release by positive samples is a specific phenomenon, we quantified myeloperoxidase (MPO) in cellular supernatants. We further assessed if a particular immune cell population (neutrophils, eosinophils, and basophils) was activated by the positive food items by flow cytometry analysis. To identify the signaling pathways that are required for DNA release we tested if specific inhibitors of key signaling pathways could block DNA release.

Results

Foods with a positive LA test result gave a higher supernatant DNA content when compared to foods with a negative result. This was specific as MPO levels were not increased by foods with a positive LA test. Protein kinase C (PKC) inhibitors resulted in inhibition of positive food stimulated DNA release. Positive foods resulted in CD63 levels greater than negative foods in eosinophils in 76.5% of tests.

Conclusion

LA test identifies food items that result in release of DNA and activation of peripheral blood innate immune cells in a PKC dependent manner, suggesting that this LA test identifies food items that result in release of inflammatory markers and activation of innate immune cells. This may be the basis for the improvement in symptoms in IBS patients who followed an LA test guided diet.

Concomitant sensitization to legumin, Fag e 2 and Fag e 5 predicts buckwheat allergy

Background

Buckwheat (Fagopyrum esculentum) has become increasingly popular as a healthy food in Europe. However, for sensitized individuals, consumption can cause anaphylactic reactions. The aim of this study was to identify individual well‐characterized buckwheat allergens for component‐resolved diagnosis.

Methods

Patients were selected by positive skin prick test to buckwheat and divided into two groups: (1) sensitized to buckwheat without clinical symptoms and (2) buckwheat allergy. Buckwheat proteins were extracted from raw buckwheat seeds, purified applying a combination of protein precipitation and chromatographic methods, and analyzed by IgE immunoblotting and ELISA.

Results

Buckwheat‐allergic patients had a significantly larger median skin prick test weal diameter for buckwheat than the sensitized group and the positive control. Also, IgE immunoblotting clearly showed a distinct pattern in sera from allergic patients when compared to sensitized individuals. Several IgE‐reactive proteins were purified from crude buckwheat extract, namely legumin (Fag e 1 plus its large subunit), Fag e 2 (2S albumin), and newly identified Fag e 5 (vicilin‐like) as well as hevein‐like antimicrobial peptides, designated Fag e 4. All four allergens showed superior diagnostic precision compared to extract‐based ImmunoCAP with high sensitivity as well as high specificity.

Conclusions

Patients with clinical symptoms clearly show a distinct allergen recognition pattern. We characterized a buckwheat vicilin‐like protein as a new relevant marker allergen, designated Fag e 5. Additionally, another new allergen, Fag e 4, potentially important for cross‐reactivity to latex was added to the allergen panel of buckwheat. Further, our data show that the full‐length legumin comprising both, large and small subunit should be applied for component‐resolved diagnosis. Our data indicate that concomitant sensitization to legumin, Fag e 2 and Fag e 5, predicts buckwheat allergy.

UK NEQAS survey of allergen component testing across the United Kingdom and other European countries

The clinical utility of molecular diagnostic approaches in allergy investigation is being recognized increasingly to play a significant role in the management of allergic patients. Determining the sensitization pattern, which is best achieved through the use of component resolved diagnostics (CRD), allows effective risk stratification, appropriate treatment and patient selection for immunotherapy. In order to assess the diagnostic service provisions for in-vitro allergy testing across Europe, a survey was carried out via the total immunoglobulin (Ig)E and specific IgE external quality assurance schemes run by UK National External Quality Assessment Service (NEQAS) Immunology, Immunochemistry and Allergy. This survey assessed allergy testing, and in particular allergen components offered by the laboratories, and found a wide variability in service provision, particularly between the United Kingdom and other European Union (EU) countries. Furthermore, there was lack of standardization for acquisition of clinical information to aid allergen (and component) selection, gating strategy, testing algorithms and clinical interpretation. Interestingly, a significant proportion of laboratories (the majority from EU) stated that they 'used' the results for peanut components for risk stratification. However, the vast majority of participants were unaware of guidelines relating to the use of allergen component testing, and agreed that further education would assist in reaching a common platform. Hence, this survey has highlighted that although CRD has been adopted into routine diagnostics across Europe, it is potentially compromised by lack of standardized protocols and guidance sources. Consequently, there is a need for local or national standards and education through External Quality Assurance services on the performance and application of CRD into allergy investigation.

Assessment of endogenous allergenicity of genetically modified plants exemplified by soybean - Where do we stand?

According to EU regulation, genetically modified (GM) plants considered to be allergenic have to be assessed concerning their endogenous allergens before placement on the EU market, in line with the international standards described in Codex Alimentarius. Under such premises, a quantitative relevant increase in allergens might occur in GM plants as an unintended effect compared with conventionally produced crops, which could pose a risk to consumers. Currently, data showing a connection between dose and allergic sensitisation are scarce since the pathophysiological mechanisms of sensitisation are insufficiently understood. In contrast, data on population dose-distribution relationships acquired by oral food challenge are available showing a connection between quantity of allergenic protein consumed and the population of allergic individuals experiencing reactions. Soybean is currently the only recognised allergenic GM food by law for which EFSA has received applications and was therefore taken as an example for defining an assessment strategy. Identification of potential allergens, methodology for quantification as well as risk assessment considerations, are discussed. A strategy is proposed for the identification, assessment and evaluation of potential hazards/risks concerning endogenous allergenicity in food derived from plants developed by biotechnology. This approach could be expanded to other allergenic foods in the future, whenever required.

Pearls and Pitfalls in Diagnosing IgE-Mediated Food Allergy

The term "food allergy" is used by many patients and clinicians to describe a range of symptoms that occur after ingestion of specific foods. However, not all symptoms occurring after food exposure are due to an allergic, or immunologic, response. It is important to properly evaluate and diagnose immunoglobulin E (IgE)-mediated food allergy as this results in reproducible, immediate onset, allergic reactions that can progress toward life-threatening anaphylaxis. Proper diagnosis requires understanding of the common foods that cause these reactions in addition to key historical elements such as symptoms, timing and duration of reaction, and risk factors that may predispose to development of IgE-mediated food allergy. Diagnostic testing for food-specific IgE can greatly aid the diagnosis. However, false-positive test results are very common and can lead to overinterpretation, misdiagnosis, and unnecessary dietary elimination. This review discusses important aspects to consider during evaluation of a patient for suspected IgE-mediated food allergy.

Identification and characterization of ovary development-related protein EJO1 (Eri s 2) from the ovary of Eriocheir sinensis as a new food allergen

SCOPE

Crab is a major source of shellfish allergens. Most studies have focused on allergens in crab muscle (CM) rather than on allergens in crab ovary (CO). This study aimed to identify potential allergens in CO from Eriocheir sinensis.

METHODS AND RESULTS

Dot blot and immunoblotting results revealed the differential reactivity of CM and CO extracts to positive sera from patients allergic to crabs. Four CO proteins showed good specific IgE-binding activities in 2-DE/immunoblotting analysis; mass spectrometry identified the proteins as hemocyanin, vitellogenin, ovary development-related protein EJO1and EJO2. The recently identified allergen EJO1 is named 'Eri s 2' in the World Health Organization and International Union of Immunological Societies (WHO/IUIS) allergen nomenclature database. Recombinant Eri s 2 exhibited good reactivity to positive sera, and pre-incubation with recombinant Eri s 2 abrogated the reactivity of positive sera from two patients to CO in a dose-dependent manner. Moreover, co-incubation of recombinant Eri s 2 with patient basophils dose-dependently promoted basophil activation, confirming the biological activity of Eri s 2.

CONCLUSION

CO tissue is an important allergen source, and Eri s 2 is a new crab allergen. This study provides insights that will be useful for component-resolved diagnostics for crab allergy.

Proteomics and its impact on food allergy diagnosis

Food allergies are a relevant health problem and symptoms range from mild to severe life-threatening reactions. With the help of up to date proteomics the causative food allergens can be identified from individual food sources. A short overview on the application of proteomics to assess the physicochemical properties of food allergens is presented.