Component-resolved Diagnostics Research Articles

Nutritional Management of Patients With Pollen Food Syndrome: Is There a Need?

Pollen food syndrome (PFS) is a highly prevalent condition causing mild oropharyngeal reactions to plant foods due to recognition by pollen-specific antibodies. It is most frequent in adults, but it can also occur in children. This review aims to establish the pitfalls of diagnosis and the nutritional consequences, and whether individuals with PFS require an individualised dietary and nutritional management strategy. The diagnosis of PFS can be made through history alone but is greatly enhanced by undertaking component-resolved diagnostic (CRD) tests to individual allergens in birch pollen and relevant foods. Management of PFS requires dietary avoidance of trigger foods, but often, many foods have to be avoided, which can affect quality of life and nutritional intake. Not all symptoms are mild, especially if concentrated forms of allergen are taken, which may occur more frequently with the increased emphasis of the health benefits of fruits and vegetables. Oral food challenge (OFC) and, in the future, novel immunotherapy may minimise necessary avoidance. Due to the high homology of the allergens involved, multiple allergy tests can result in mass exclusion of antioxidant-rich fruits and vegetables, which are important nutritional contributors to the diet. Thus, those with PFS should receive individual dietary counselling to prevent deficiency diseases, especially expectant mothers, children and those who are avoiding multiple foods.

Gly m 5/Gly m 8 fusion component as a potential novel candidate molecule for diagnosing soya bean allergy in Japanese children.

Soya bean is a major food allergen in children. Component-resolved diagnostics has improved the accuracy of diagnosing immunoglobulin E (IgE)-mediated food allergies. We aimed to develop a novel component for the diagnosis of soya bean allergy using recombinant technology. Japanese paediatric patients with suspected soya bean allergy (n=91) were included, and symptomatic (n=40) and asymptomatic (n=51) cases were divided through oral food challenge testing. Specific IgE (sIgE) antibodies to each recombinant allergen component were analysed by enzyme-linked immunosorbent assay, and the diagnostic performances of the components were assessed by area under the receiver operating characteristic curves (AUC). Among the recombinant components, sIgE antibody levels to Gly m 8 showed the highest AUC (0.706). A combination of Gly m 8 and α' subunit of Gly m 5, improved the diagnostic performance of the single components. Moreover, the N-terminal extension region of α' subunit of Gly m 5, which has low cross-reactivity among the vicilins, showed higher diagnostic performance (AUC 0.695) than the full-length α' subunit of Gly m 5 (AUC 0.613). Based on these findings, we developed a fusion protein of Gly m 8 plus the extension region of α' subunit of Gly m 5; this fusion protein was very efficient for diagnosing soya bean allergy (AUC 0.801). A fusion protein of Gly m 8 and the extension region of α' subunit of Gly m 5 could potentially diagnose soya bean allergy in paediatric patients. Fusion proteins may be useful for producing novel allergen components with improved diagnostic value.

Underestimation of house dust mite–specific IgE with extract-based ImmunoCAPs compared with molecular ImmunoCAPs

Underestimation of house dust mite–specific IgE with extract-based ImmunoCAPs compared with molecular ImmunoCAPs

How to diagnose food allergy.

To assess the recent studies that focus on specific immunoglobulin E (sIgE) testing and basophil activation test (BAT) for diagnosing IgE-mediated food allergies. The sIgE to allergen extract or component can predict reactivity to food. The cutoff value based on the positive predictive value (PPV) of sIgE can be considered whenever deciding whether oral food challenge (OFC) is required to diagnose hen's egg, cow's milk, wheat, peanut, and cashew nut allergy. However, PPV varies depending on the patients' background, OFC methodology, challenge foods, and assay methodology. Component-resolved diagnostics (CRD) has been used for food allergy diagnosis. Ovomucoid and omega-5 gliadin are good diagnostic markers for heated egg and wheat allergy. More recently, CRD of peanut, tree nuts, and seed have been investigated. Ara h 2 showed the best diagnostic accuracy for peanut allergy; other storage proteins, such as Jug r 1 for walnut, Ana o 3 for cashew nut, Ses i 1 for sesame, and Fag e 3 for buckwheat, are also better markers than allergen extracts. Some studies suggested that BAT has superior specificity than skin prick test and sIgE testing. The sIgE testing and BAT can improve diagnostic accuracy. CRD provides additional information that can help determine whether OFCs should be performed to diagnose food allergy.

Seafood allergy: A comprehensive review of fish and shellfish allergens

Seafood refers to several distinct groups of edible aquatic animals including fish, crustacean, and mollusc. The two invertebrate groups of crustacean and mollusc are, for culinary reasons, often combined as shellfish but belong to two very different phyla. The evolutionary and taxonomic diversity of the various consumed seafood species poses a challenge in the identification and characterisation of the major and minor allergens critical for reliable diagnostics and therapeutic treatments. Many allergenic proteins are very different between these groups; however, some pan-allergens, including parvalbumin, tropomyosin and arginine kinase, seem to induce immunological and clinical cross-reactivity.This extensive review details the advances in the bio-molecular characterisation of 20 allergenic proteins within the three distinct seafood groups; fish, crustacean and molluscs. Furthermore, the structural and biochemical properties of the major allergens are described to highlight the immunological and subsequent clinical cross-reactivities. A comprehensive list of purified and recombinant allergens is provided, and the applications of component-resolved diagnostics and current therapeutic developments are discussed.

Mast cell activation test in the diagnosis of allergic disease and anaphylaxis

BackgroundFood allergy is an increasing public health issue and the most common cause of life-threatening anaphylactic reactions. Conventional allergy tests assess for the presence of allergen-specific IgE, significantly overestimating the rate of true clinical allergy and resulting in overdiagnosis and adverse effect on health-related quality of life.ObjectiveTo undertake initial validation and assessment of a novel diagnostic tool, we used the mast cell activation test (MAT).MethodsPrimary human blood-derived mast cells (MCs) were generated from peripheral blood precursors, sensitized with patients' sera, and then incubated with allergen. MC degranulation was assessed by means of flow cytometry and mediator release. We compared the diagnostic performance of MATs with that of existing diagnostic tools to assess in a cohort of peanut-sensitized subjects undergoing double-blind, placebo-controlled challenge.ResultsHuman blood-derived MCs sensitized with sera from patients with peanut, grass pollen, and Hymenoptera (wasp venom) allergy demonstrated allergen-specific and dose-dependent degranulation, as determined based on both expression of surface activation markers (CD63 and CD107a) and functional assays (prostaglandin D2 and β-hexosaminidase release). In this cohort of peanut-sensitized subjects, the MAT was found to have superior discrimination performance compared with other testing modalities, including component-resolved diagnostics and basophil activation tests. Using functional principle component analysis, we identified 5 clusters or patterns of reactivity in the resulting dose-response curves, which at preliminary analysis corresponded to the reaction phenotypes seen at challenge.ConclusionThe MAT is a robust tool that can confer superior diagnostic performance compared with existing allergy diagnostics and might be useful to explore differences in effector cell function between basophils and MCs during allergic reactions.

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

BackgroundComponent‐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.MethodsWe 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.ResultsEleven 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.ConclusionSelected 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 diagnostics demonstrates that most peanut-allergic individuals could potentially introduce tree nuts to their diet.

Nut allergy varies from pollen cross-allergy, to primary severe allergy with life-threatening symptoms. The screening of IgE antibodies to a wide spectrum of allergens, including species-specific and cross-reactive allergens, is made possible via microarray analysis. We sought to study the association of variable IgE sensitization profiles to clinical response in peanut-challenged children and adolescents in a birch-endemic region. In addition, we studied the avoidance of tree nuts and species-specific sensitizations. We studied 102 peanut-sensitized patients who underwent a double-blind placebo-controlled challenge to peanut. We analysed ISAC ImmunoCAP microarray to 112 allergens, singleplex ImmunoCAPs for hazelnut Cor a 14 and cashew Ana o 3, and performed skin prick tests to peanut, tree nuts and sesame seed. We surveyed avoidance diets with a questionnaire. Sensitization to PR-10 proteins was frequent (Bet v 1 90%), but equally high in the challenge negatives and positives. IgE to Ara h 2 and Ara h 6 discriminated peanut allergic (n=69) and tolerant (n=33) the best. Avoidance of tree nuts was common (52% to 96%), but only 6% to 44% presented species-specific sensitizations to tree nuts, so a great number could potentially introduce these species into their diet. PR-10-sensitizations were frequent and strong regardless of peanut allergy status. Component-resolved diagnostics can be employed to demonstrate to patients that sensitization to seed storage proteins of tree nuts is uncommon. Several tree nuts could potentially be reintroduced to the diet.

Component-resolved diagnostics to direct in venom immunotherapy: Important steps towards precision medicine.

Stings of Hymenoptera can induce IgE-mediated systemic and even fatal allergic reactions. Venom-specific immunotherapy (VIT) is the only disease-modifying and curative treatment of venom allergy. However, choosing the correct venom for VIT represents a necessary prerequisite for efficient protection against further anaphylactic sting reactions after VIT. In the past, therapeutic decisions based on the measurement of specific IgE (sIgE) levels to whole venom extracts were not always straightforward, especially when the patient was not able to identify the culprit insect. In the last years, the increasing knowledge about the molecular structure and relevance of important venom allergens and their availability as recombinant allergens, devoid of cross-reactive carbohydrate determinants, resulted in the development of an advanced component-resolved diagnostics (CRD) approach in venom allergy. Already to date, CRD has increased the sensitivity of sIgE detection and enabled the discrimination between primary sensitization and cross-reactivity, particularly in patients with sensitization to both honeybee and vespid venom. Hence, CRD in many patients improves the selection of the appropriate immunotherapeutic intervention. Moreover, the detailed knowledge about sensitization profiles on a molecular level might open new options to identify patients who are at increased risk of side-effects or not to respond to immunotherapy. Therefore, increasing potential of CRD becomes evident, to direct therapeutic decisions in a personalized and patient-tailored manner. Reviewed here are the state of the art options, recent developments and future perspectives of CRD of Hymenoptera venom allergy.

Usefulness of Component-resolved diagnostics (CRD) in predicting hazelnut allergy in Japanese children

There have been no report of hazelnut allergy in Japan, while allergy to tree nuts are relatively common. Cor a 9 and Cor a 14 may be responsible for systemic reactions to hazelnut in Europe. We hypothesized that component-resolved diagnostics (CRD) would predict the result of hazelnut oral food challenge (OFC) in Japanese children. We recruited 71 subjects (median age: 7.8 years) who were sensitized to hazelnut and performed a hazelnut OFC at Sagamihara National Hospital from 2007 to 2017. OFCs were performed using roasted hazelnut. The sIgE levels (hazelnut/Cor a 1/Cor a 8/Cor a 9/Cor a 14/ alder pollen) were measured using ImmunoCAP. We investigated the predictive factors of a positive hazelnut OFC. Seven subjects (10%) had a positive OFC, and 3 had systemic reactions. The sIgE to hazelnut/Cor a 1/ Cor a 8/Cor a 9/Cor a 14/ alder pollen were 9.3/13.9/4.63/0.05/0.84 /0.10 (median, UA/ml). Hazelnut sIgE was strongly correlated with both Cor a 1 and alder pollen (r=0.76/ 0.74). The sIgE to Cor a 1/alder pollen in OFC positive subjects were significantly lower than those in OFC negative subjects (1.61 vs.14.8, p=0.028, 0.05 vs. 6.07, p=0.029). The area under the receiver operating characteristics curve for hazelnut/Cor a 1/Cor a 8/Cor a 9/Cor a 14/alder pollen was 0.69/0.75/0.56 /0.59/0.69/0.75 (p=0.09/0.03/0.60/0.41/0.09/0.03). Additional evaluation of sIgE to Cor a 1 or alder pollen seems to improve accuracy in diagnosis of hazelnut allergy in Japanese children sensitized to hazelnut.

The high molecular weight dipeptidyl peptidase IV Pol d 3 is a major allergen of Polistes dominula venom

Hymenoptera venom allergy can cause severe anaphylaxis in untreated patients. Polistes dominula is an important elicitor of venom allergy in Southern Europe as well as in the United States. Due to its increased spreading to more moderate climate zones, Polistes venom allergy is likely to gain importance also in these areas. So far, only few allergens of Polistes dominula venom were identified as basis for component-resolved diagnostics. Therefore, this study aimed to broaden the available panel of important Polistes venom allergens. The 100 kDa allergen Pol d 3 was identified by mass spectrometry and found to be a dipeptidyl peptidase IV. Recombinantly produced Pol d 3 exhibited sIgE-reactivity with approximately 66% of Polistes venom-sensitized patients. Moreover, its clinical relevance was supported by the potent activation of basophils from allergic patients. Cross-reactivity with the dipeptidyl peptidases IV from honeybee and yellow jacket venom suggests the presence of exclusive as well as conserved IgE epitopes. The obtained data suggest a pivotal role of Pol d 3 as sensitizing component of Polistes venom, thus supporting its status as a major allergen of clinical relevance. Therefore, Pol d 3 might become a key element for proper diagnosis of Polistes venom allergy.

Isotype-specific agglutination-PCR (ISAP): A sensitive and multiplex method for measuring allergen-specific IgE

Isotype-specific agglutination-PCR (ISAP): A sensitive and multiplex method for measuring allergen-specific IgE

Diagnostic relevance of IgE sensitization profiles to eight recombinant Phleum pratense molecules.

Grass pollen-related seasonal allergic rhinoconjunctivitis (SARg) is clinically heterogeneous in severity, comorbidities, and response to treatment. The component-resolved diagnostics disclosed also a high heterogeneity at molecular level. Our study aimed at analyzing the characteristics of the IgE sensitization to Phleum pratense molecules and investigating the diagnostic relevance of such molecules in childhood. We examined 1120 children (age 4-18years) with SARg. Standardized questionnaires on atopy were acquired through informatics platform (AllergyCARD™). Skin prick tests were performed with pollen extracts. Serum IgE to airborne allergens and eight P.pratense molecules (rPhl p 1, rPhl p 2, rPhl p 4, rPhl p 5b, rPhl p 6, rPhl p 7, rPhl p 11, rPhl p 12) were tested by ImmunoCAP FEIA. The analysis of IgE responses against eight P.pratense molecules showed 87 profiles. According to the number of molecules recognized by IgE, the more complex profiles were characterized by higher serum total IgE, higher grass-specific serum IgE, and higher number and degree of sensitization to pollens. The most frequent IgE sensitization profile was the monomolecular Phl p 1. Sensitization to Phl p 7 was a reliable biomarker of asthma, whereas Phl p 12 of oral allergy syndrome. Sensitization to Phl p 7 was associated with a higher severity of SARg, and complex profiles were associated with longer disease duration. In a large pediatric population, the complexity of IgE sensitization profiles against P.pratense molecules is related to high atopic features although useless for predicting the clinical severity. The detection of serum IgE to Phl p 1, Phl p 7, and Phl p 12 can be used as clinical biomarkers of SARg and comorbidities. Further studies in different areas are required to test the impact of different IgE molecular profiles on AIT response.

Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management

This review provides general information to serve as a primer for those embarking on understanding food allergy and also details advances and updates in epidemiology, pathogenesis, diagnosis, and treatment that have occurred over the 4years since our last comprehensive review. Although firm prevalence data are lacking, there is a strong impression that food allergy has increased, and rates as high as approximately 10% have been documented. Genetic, epigenetic, and environmental risk factors are being elucidated increasingly, creating potential for improved prevention and treatment strategies targeted to those at risk. Insights on pathophysiology reveal a complex interplay of the epithelial barrier, mucosal and systemic immune response, route of exposure, and microbiome among other influences resulting in allergy or tolerance. The diagnosis of food allergy is largely reliant on medical history, tests for sensitization, and oral food challenges, but emerging use of component-resolved diagnostics is improving diagnostic accuracy. Additional novel diagnostics, such as basophil activation tests, determination of epitope binding, DNA methylation signatures, and bioinformatics approaches, will further change the landscape. Anumber of prevention strategies are under investigation, but early introduction of peanut has been advised as a public health measure based on existing data. Management remains largely based on allergen avoidance, but a panoply of promising treatment strategies are in phase 2 and 3 studies, providing immense hope that better treatment will be imminently and widely available, whereas numerous additional promising treatments are in the preclinical and clinical pipeline.

New trends in anaphylaxis.

This review presents the current trends in anaphylaxis management discussed at the fourth International Network for Online-Registration of Anaphylaxis (NORA) conference held in Berlin in April 2017. Current data from the anaphylaxis registry show that Hymenoptera venom, foods, and pharmaceutical drugs are still among the most frequent triggers of anaphylaxis. Rare triggers include chicory, cardamom, asparagus, and goji berries. A meta-analysis on recent trends in insect venom anaphylaxis demonstrated for the first time that, although data on the efficacy of insect venom immunotherapy is limited, the occurrence of severe reactions upon repeated sting events can be prevented and patients’ quality of life improved. Molecular diagnostics of insect venom anaphylaxis have significantly improved diagnostic sensitivity and specificity. Self-treatment of anaphylaxis is of great importance. Recent data from the anaphylaxis registry show an increase (from 23% in 2012 to 29% in 2016) in the use of adrenaline as recommended in the guidelines. A survey on the implementation of guidelines conducted among the centers reporting to the anaphylaxis registry highlights the extent to which the guideline has been perceived and implemented. Reports on a variety of cases in the anaphylaxis registry illustrate the diversity of this potentially life-threatening reaction. Component-resolved diagnostics can help to specify sensitization profiles in anaphylaxis, particularly in terms of the risk for severe reactions. Recent studies on anaphylaxis awareness show that training methods are effective; nevertheless, target groups and learning methods need to undergo further scientific investigation in coming years.

The benefit of molecular diagnostics in allergic rhinitis

Molecular component-resolved diagnostics has established itself in recent years as an integral part of the routine diagnosis of allergic rhinitis. A systematic literature review was performed. By using allergen components appropriately, it is possible to identify IgE sensitizations to specific marker allergens and to crossreactive allergens and this way explain polysensitizations obtained in extract-based diagnostics. The detection of individual molecular sensitization patterns enables better classification of the clinical symptoms, thus enhancing the possibility of individual, personalized treatment planning. This implies greater diagnostic reliability for specific immunotherapy, which should in turn result in a better treatment response—despite there being no scientific evidence of this as yet. In spite of the immense expansion of our knowledge in the field of component-resolved diagnostics, the clinical relevance of molecular findings still needs to be consistently assessed on the basis of the individual patient’s symptoms. This paper is intended to provide a guide to—and highlight possible courses of action when—making appropriate use of individual components in the diagnosis of allergic rhinitis.

Component resolved diagnostics for hymenoptera venom allergy.

Purpose of reviewComponent-resolved diagnostics makes use of defined allergen molecules to analyse IgE-mediated sensitizations at a molecular level. Here, we review recent studies on the use of component-resolved diagnostics in the field of Hymenoptera venom allergy (HVA) and discuss its benefits and limitations.Recent findingsComponent resolution in HVA has moved from single molecules to panels of allergens. Detection of specific immunoglobulin E (sIgE) to marker and cross-reactive venom allergens has been reported to facilitate the discrimination between primary sensitization and cross-reactivity and thus, to provide a better rationale for prescribing venom immunotherapy (VIT), particularly in patients sensitized to both honeybee and vespid venom. Characterization of IgE reactivity to a broad panel of venom allergens has allowed the identification of different sensitization profiles that in honeybee venom allergy were associated with increased risks for side effects or treatment failure of VIT. In contrast, component resolution so far has failed to provide reliable markers for the discrimination of sensitizations to venoms of different members of Vespidae.SummaryComponent-resolved diagnostics allows a better understanding of the complexity of sensitization and cross-reactivities in HVA. In addition, the enhanced resolution and precision may allow identification of biomarkers, which can be used for risk stratification in VIT. Knowledge about the molecular composition of different therapeutic preparations may enable the selection of appropriate preparations for VIT according to individual sensitization profiles, an approach consistent with the goals of personalized medicine.

A critical analysis of the utility of component tests in the diagnosis of pollen‐related peanut and hazelnut allergy in the context of the BSACI guideline

We congratulate the authors for producing a comprehensive guideline on the diagnosis and management of peanut and tree nut allergy(1) This is likely to improve care via standardisation across the UK NHS Allergy services. Several studies have illustrated the benefit of component resolved diagnostic (CRD) testing by enhancing the accuracy of peanut and hazelnut allergy diagnosis and aiding the process of risk stratification. However, most of these data are derived from studies carried out on children in Europe and USA with little evidence from adults and the British population. This article is protected by copyright. All rights reserved.

Respiratory Allergens from Furred Mammals: Environmental and Occupational Exposure.

Furry mammals kept as pets, farm and laboratory animals are important allergen sources. The prevalence of sensitization to furred mammals appears to be increasing worldwide. Several mammalian allergens from diverse species are well characterized with regard to their molecular structure and immunogenicity, and some are already available for component-resolved allergy diagnostics. The distribution of various mammalian allergens has been extensively studied during the past few decades. Animal allergens were found to be ubiquitous in the human environment, even in places where no animals reside, with concentrations differing considerably between locations and geographical regions. This review presents an overview of identified mammalian respiratory allergens classified according to protein families, and compiles the results of allergen exposure assessment studies conducted in different public and occupational environments.

Molecular allergy diagnostic tests: development and relevance in clinical practice.

Molecular allergy is based on identification, characterization and subsequent use of single allergens, being components of complex allergen sources like pollen, mites, furred animals, foods or insect venoms. Only few protein families contain relevant allergens of similar sequence and structure, carrying common IgE epitopes as the basis of cross reactivity. Used as purified or recombinant (glyco)proteins single allergens can potentially improve in-vitro diagnostics, particularly allergen-specific IgE assays through a) increased sensitivity, b) use of risk and marker allergens, c) component-resolved diagnostics (CRD). CRD can differentiate primary, species-specific from secondary, cross-reactive sensitizations to single allergens. Allergen components facilitate an increased analytical sensitivity, particularly if they are underrepresented or missing in conventional allergen extracts. They are mainly used in single assays (singleplex) for the detection of IgE, but also in a microarray format (multiplex) with 112 components from 50 allergen sources with slightly decreased analytical sensitivity. Concepts of molecular allergy can only be separately defined and utilized for each allergen source (pollen, mites, foods or insect venoms). As soon as essential singe allergens are available, their specific role in diagnostics should be defined. This requires well characterized patient cohorts from various countries, since exposure, allergic immune response and clinical relevance can vary substantially between individual subjects and geographical regions. The patient’s clinical information is essential for proper interpretation of molecular allergology results. The history and/or challenge test results will finally provide evidence, in how far a sensitization to single allergens might be clinically relevant or not.