Evaluation of a novel automated allergy microarray platform compared with three other allergy test methods

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.

Precision medicine in the allergy clinic: the application of component resolved diagnosis

INTRODUCTION

A precise diagnosis is key for the optimal management of allergic diseases and asthma. In vivo or in vitro diagnostic methods that use allergen extracts often fail to identify the molecules eliciting the allergic reactions.

AREAS COVERED

Component-resolved diagnosis (CRD) has solved most of the limitations of extract-based diagnostic procedures and is currently valuable tool for the precision diagnosis in the allergy clinic, for venom and food allergy, asthma, allergic rhinitis, and atopic dermatitis. Its implementation in daily practice facilitates: a) the distinction between genuine multiple sensitizations and cross-reactive sensitization in polysensitized patients; b) the prediction of a severe, systemic reaction in food or insect venom allergy; c) the optimal selection of allergen immunotherapy based on the patient sensitization profile. This paper describes its main advantages and disadvantages, cost-effectiveness and future perspectives.

EXPERT OPINION

The diagnostic strategy based on CRD is part of the new concept of precision immunology, which aims to improve the management of allergic diseases.

Allergen extract- and component-based diagnostics in children of the ALLIANCE asthma cohort

BACKGROUND

Current in vitro allergen-specific IgE (sIgE) detection assays measure IgE against allergen extracts or molecules in a single- or multiplex approach. Direct comparisons of the performance of such assays among young children with common presentations of allergic diseases regardless of sensitization status are largely missing.

OBJECTIVES

The aim of this study was a comparison of the analytical and diagnostic performance for common clinical questions of three commonly used technologies which rely upon different laboratory methodologies among children of the All Age Asthma (ALLIANCE) cohort (clinicaltrials.gov: NCT02496468).

METHODS

Sera from 106 paediatric study participants (mean age 4 years) were assessed for the presence of sIgE by means of the ImmunoCAP™ sx1 and fx5 mixes, the ImmunoCAP ISAC™ 112 microarray and a Euroline™ panel.

RESULTS

Total and negative concordance was high (>82%->89%), while positive concordance varied considerably (0%-100%) but was also >50% for the most common sensitizations analysed (house dust mite and birch). All three test systems showed good sensitivity and specificity (AUC consistently > 0.7). However, no significant differences with regard to identifying sIgE sensitizations associated with symptoms in children with suspected pollen- or dust-triggered wheeze or presenting with symptoms of allergic rhinoconjunctivitis or food allergy were detected. Extending the number of allergens did not change the similar performance of the three assay systems.

CONCLUSION AND CLINICAL RELEVANCE

Among young children, the three sIgE assays showed good analytical and diagnostic concordance. Our results caution that the identification of larger numbers of sensitizations by more comprehensive multiplex approaches may not improve the clinical utility of sIgE testing in this age group.

The use of microarray and other multiplex technologies in the diagnosis of allergy

OBJECTIVE

To give an overview and describe the strengths and weaknesses of immunoglobulin E (IgE) microarray and other multiplex assays that have been developed and are being used for allergy diagnostics.

DATA SOURCES

Queries for IgE microarray and multiplex assays were conducted with PubMed and Google Scholar, searching for primary articles and review papers.

STUDY SELECTIONS

We focused on articles written in English on commercially available IgE multiplex assays that were reported in the allergy and immunology literature.

RESULTS

Several commercial IgE assays that use microarray or other multiplex technology have been developed, and some have been implemented into clinical practice in Europe and Asia, with the Immuno Solid-Phase Allergen Chip being the most widely studied. Results of these assays generally correlate with results using "singleplex" IgE assays (eg, ImmunoCAP), though there can be variability among products and among allergens. A strength of the microarray technology is that IgE to a large number of allergens can be detected simultaneously in a single test, and only a small amount of patient serum is required. Cost, inadequate sensitivity under some scenarios, and difficulties with data interpretation, in some cases of 100 or more allergens, can be limitations.

CONCLUSION

IgE microarray assays are already a valuable tool in research applications. These assays, and also other forms of IgE multiplex assays, are likely to play an important role in the clinical practice of allergy in the future. Additional studies focused on clinical outcomes, and the development of more targeted allergen panels could facilitate increased clinical use.

Epitope Mapping of Food Allergens Using Noncontact Piezoelectric Microarray Printer

Peptide microarrays have been used to study protein-protein interaction, enzyme-substrate profiling, epitope mapping, vaccine development, and immuno-profiling. Unlike proteins, peptides are cheap to produce, and can be produced in a high-throughput manner, in a reliable and consistent procedure that reduces batch-to-batch variability. All this provides the peptide microarrays a great potential in the development of new diagnostic tools. Noncontact printing, such as piezoelectric systems, results in a considerable advance in protein and peptide microarray production. In particular, they improve drop deposition, sample distribution, quality control, and flexibility in substrate deposition and eliminate cross-contamination and carryover. These features contribute to creating reproducible assays and generating more reliable data. Here we describe the methods and materials for epitope mapping of food allergens using peptide microarrays produced with a noncontact piezoelectric microarray printer.

Sensitization to Molecular Components in 104 Atopic Dermatitis Patients in Relation to Subgroups of Patients Suffering from Bronchial Asthma and Allergic Rhinitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease. The progression from AD to bronchial asthma (AB) and allergic rhinitis (AR) is called atopic march. The aim of this study was to evaluate the difference in the sensitization to molecular components in patients suffering from AD in relation to subgroups of patients with AR and AB.

MATERIAL AND METHODS

The complete dermatological and allergological examinations were performed. Specific IgE antibodies against 112 molecular components were measured with the multiplex ImmnoCAP ISAC test.

RESULTS

Altogether 104 atopic dermatitis patients (50 men, 54 women) at the average age 40.1 years were examined. The sensitization to molecular components was confirmed in 93.3% of patients. The sensitization to components of mites, grasses, trees, animals, moulds, and shrimps was significantly more frequent in patients with severe form of AD and the sensitization to components of grasses, trees, and moulds was significantly higher in subgroup of patients with AB. In subgroup of patients suffering from AR the higher occurrence of pollen-derived and pollen-food derived PR-10 proteins, grasses, mites, and animals was observed also.

CONCLUSIONS

We have confirmed the significant differences in the sensitization to molecular components in patients suffering from severe form of AD, and in subgroups of patients suffering from AB and AR. These molecular components may play the important role in the consecutive development of different allergy pathologies called atopic march.

IgE cross-reactivity measurement of cashew nut, hazelnut and peanut using a novel IMMULITE inhibition method

Background Tree nut-allergic individuals are often sensitised towards multiple nuts and seeds. The underlying cause behind a multi-sensitisation for cashew nut, hazelnut, peanut and birch pollen is not always clear. We investigated whether immunoglobulin E antibody (IgE) cross-reactivity between cashew nut, hazelnut and peanut proteins exists in children who are multi-allergic to these foods using a novel IMMULITE®-based inhibition methodology, and investigated which allergens might be responsible. In addition, we explored if an allergy to birch pollen might play a role in this co-sensitisation for cashew nut, hazelnut and peanut. Methods Serum of five children with a confirmed cashew nut allergy and suffering from allergic symptoms after eating peanut and hazelnut were subjected to inhibition immunoassays using the IMMULITE® 2000 XPi. Serum-specific IgE (sIgE) to seed storage allergens and pathogenesis-related protein 10 (PR10) allergens were determined and used for molecular multicomponent allergen correlation analyses with observed clinical symptoms and obtained inhibition data. Results IgE cross-reactivity was observed in all patients. Hazelnut extract was a strong inhibitor of cashew nut sIgE (46.8%), while cashew nut extract was less able to inhibit hazelnut extract (22.8%). Peanut extract showed the least inhibition potency. Moreover, there are strong indications that a birch pollen sensitisation to Bet v 1 might play a role in the observed symptoms provoked upon ingestion of cashew nut and hazelnut. Conclusions By applying an adjusted working protocol, the IMMULITE® technology can be used to perform inhibition assays to determine the risk of sIgE cross-reactivity between very different food components.

A Comparison of Multiple Allergen Simultaneous Tests Using Allergen-Specific IgE Concentration and Intradermal Skin Tests in Atopic Horses With Pollen Allergy

Intradermal tests (IDTs) and measurement of specific immunoglobulin E class (sIgE) levels in sera are the most common and reliable methods used in allergological clinical practice. The purpose of this study was to explore the sensitization of pollen allergy in atopic horses with pollinosis and to assess the diagnostic value of the multiple allergen simultaneous tests (MASTs) compared with that of the IDT. Twenty-one Malopolski horses with typical skin hypersensitivity symptoms during pollen seasons were enrolled. Intradermal tests were performed, and allergen-specific IgE concentrations in sera were measured using a monoclonal anti-IgE antibody to pollens of grass, weeds, trees, and cultivated plants. The highest sensitization rate was for Secale cereale (IDT, 76%; MAST, 66.7%), grass (IDT, 71%; MAST, 57%), and Brassica napus (IDT, 52.4%; MAST, 57%). Receiver operating characteristic (ROC) curve analysis and the area under the ROC curve (AUC) showed that Betula spp., Alnus spp., and Corylus spp. had the highest AUC at 0.854, followed by Secale cereale (AUC = 0.796), Plantago lanceolata (AUC = 0.726), Brassica napus (AUC = 0.704), and a grass allergen mixture (AUC = 0.695). The mean AUC for all allergens was 0.712 (0.604-0.867). The overall sensitivity of the sIgE plant horse panel was 78% (range, 68%-90%), the specificity was 86.3% (range, 64%-100%), and the accuracy was 79% (range, 64%-87%). Statistical kappa (κ) agreement between the MAST and IDT was reached for tree (κ = 0.767), rye (κ = 0.687), colza (κ = 0.671), and grass (κ = 0.664) pollen. The MAST showed a favorable agreement with the IDT and can be used for the detection of sIgE in atopic horses with pollinosis.

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.

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.

Microarray Immunodiagnostics for Aeroallergens

PURPOSE OF REVIEW

The impact of new technologies, especially multiplexed molecular allergy diagnostics based on allergen arrays, on the management of complex patients with respiratory allergies has been important.

RECENT FINDINGS

Currently, the detailed characteristics of the IgE profile of the patient, such as sensitization to genuine or cross-reacting components or the sensitization to potentially harmful allergens, allow an allergist to tailor treatment in the context of precision medicine rules. A number of relevant articles have been published in recent years on this topic, and, in this review, the new added values of allergen array-based diagnostics are reported.

Precision medicine allergy immunoassay methods for assessing immunoglobulin E sensitization to aeroallergen molecules

Molecular-based allergy diagnosis for the in vitro assessment of a patient immunoglobulin E (IgE) sensitization profile at the molecular level uses allergen molecules (also referred to as allergen components), which may be well-defined, highly purified, natural allergen components or recombinant allergens. Modern immunoassay methods used for the detection of specific IgE against aeroallergen components are either singleplex (such as the fluorescence enzyme immunoassay with capsulated cellulose polymer solid-phase coupled allergens, the enzyme-enhanced chemiluminescence immunoassay and the reversed enzyme allergosorbent test, with liquid-phase allergens), multiparameter (such as the line blot immunoassay for defined partial allergen diagnostics with allergen components coating membrane strips) or multiplex (such as the microarray-based immunoassay on immuno solid-phase allergen chip, and the two new multiplex nanotechnology-based immunoassays: the patient-friendly allergen nano-bead array, and the macroarray nanotechnology-based immunoassay used as a molecular allergy explorer). The precision medicine diagnostic work-up may be organized as an integrated “U-shape” approach, with a “top-down” approach (from symptoms to molecules) and a “bottom-up” approach (from molecules to clinical implications), as needed in selected patients. The comprehensive and accurate IgE sensitization molecular profiling, with identification of the relevant allergens, is indicated within the framework of a detailed patient’s clinical history to distinguish genuine IgE sensitization from sensitization due to cross-reactivity (especially in polysensitized patients), to assess unclear symptoms and unsatisfactory response to treatment, to reveal unexpected sensitizations, and to improve assessment of severity and risk aspects in some patients. Practical approaches, such as anamnesis molecular thinking, laboratory molecular thinking and postmolecular anamnesis, are sometimes applied. The component-resolved diagnosis of the specific IgE repertoire has a key impact on optimal decisions making for prophylactic and specific immunotherapeutic strategies tailored for the individual patient.

Component-Resolved Diagnosis in Allergic Rhinitis and Asthma

BACKGROUND

Allergic rhinitis and asthma are highly prevalent chronic inflammatory diseases leading to restrictions in the patient's quality of life and high costs for healthcare systems. Both diseases are associated with the presence of specific IgE (sIgE) against aeroallergens. This review aims to examine the importance of molecular allergy diagnostics in the assessment and management of these disorders.

CONTENT

The "U-shaped" approach, proposed by the European Academy of Allergy and Clinical Immunology, combines conventional allergy diagnostics with the benefits of component-resolved diagnosis (CRD) and offers important additional information regarding the patient's sensitization pattern, especially in complex clinical cases such as polysensitization or idiopathic reactions, thus avoiding overuse of in vitro and in vivo IgE diagnostics. CRD may help the clinician to identify the cause of an allergy and, in the case of complex polysensitization, uncover possible cross-reactivity. Polysensitization, especially to inhalant allergens, is associated with the clinical appearance of asthma and allergic rhinitis; important risk factors for the latter are the major allergens Fel d 1 and Can f 1. Importantly, information on molecular sensitization patterns significantly influences the choice of specific immunotherapy and reduces its overprescription.

CONCLUSION

At present, allergy diagnostics largely rely on clinical history, physical examination, and in vivo IgE testing. However, in vitro diagnostics including CRD are currently finding their way into the clinical routine and can offer additional information on the patient's sensitization profile and treatment responsiveness.

Allergy diagnosis from symptoms to molecules, or from molecules to symptoms: a comparative clinical study

Background

Classical allergy diagnostic workup “from symptoms to molecules” comprises 1) clinical investigation, 2) skin prick- and IgE- testing, and recently, 3) molecular allergy testing. We aimed to examine the diagnostic fidelity of the alternative approach “from molecules to symptoms”, which was recently suggested in the EAACI Molecular Allergology User’s Guide, in a retrospective clinical study.

Methods

Records from 202 patients with clinically suspected allergic sensitizations were extracted from files at two sites applying either the “ISAC-first” workup with IgE-testing by immuno-solid phase allergen chip ISAC112 followed by selected skin prick tests (SPT) or the “SPT-first” starting with SPT followed by the microarray test.

Results

In the ISAC-first procedure significantly less SPTs were performed during allergy diagnosis (median 4 vs. 14). By SPT in 19% of patients in the ISAC-first group and in 34% in the SPT-first group additional respiratory allergens (p = 0.014) were detected not positive in ISAC microarray. By ISAC microarray test 18% additional sensitizations were found in the ISAC-first, and 32% in SPT-first cohort (p = 0.016). For food allergens 13 and 12% additional sensitizations were detected by the microarray not detected by SPT in the two groups (p = 0.800). No additional food allergen was found by SPT in the ISAC-first group, while in 6% of the cases in the SPT-first group detected sensitizations were negative in the microarray.

Discussion

The ISAC-first approach followed by (fewer) SPTs meets the demands for a patient’s tailored diagnostic work-up and therefore can be considered equivalent to the conventional way using the skin prick test as first screening tool, followed by IgE diagnosis.

Conclusions

For the diagnostic verification of clinically suspected allergy, the novel concept “from molecules to clinic” offers a reliable diagnostic workup in shorter time. Due to lower skin test numbers it is especially applicable for young children and seniors, in atopic patients, and whenever skin tests get difficult or unreliable.

Electronic supplementary material

The online version of this article (10.1186/s40413-018-0199-y) contains supplementary material, which is available to authorized users.

Sensitization to PR-10 proteins is indicative of distinctive sensitization patterns in adults with a suspected food allergy

Background

The extent of co-sensitization within and between food protein families in an adult population is largely unknown. This study aimed to identify the most frequently recognized components in the PR-10 and storage protein family, as well as patterns in (co-)sensitization, in a birch-endemic area.

Methods

Results of ImmunoCAP ISAC, performed during routine care in Dutch adult outpatients suspected of food allergy, were collected.

Results

A total of 305 patients were selected, aged 16–79 years (median 32 years). Sensitization to one or more PR-10 proteins was most frequent (74% of all subjects), followed by 35% to storage protein and 15% to nsLTPs. Within the PR-10 family, subjects were most often sensitized to Bet v 1 (73% of 305), Cor a 1.04 (72%) and Mal d 1 (68%). Sensitization to PR-10s from soy, celery and kiwi occurred distinctively less often (< 55% of Bet v 1 sensitized subjects) compared to other food PR-10s (all > 70%). Subjects sensitized to these ‘less common PR-10 proteins’ were sensitized to more food and inhalant components on the ISAC, compared to subjects sensitized to ‘common PR-10 proteins’ (median 22 vs 13 out of 112, p < 0.0001). Seven subjects demonstrated sensitization to food PR-10 proteins, without concomitant sensitization to pollen PR-10s. Within the storage proteins, sensitization to multiple peanut allergens was most common (on average 3 out of 4).

Conclusions

Sensitization to PR-10 food proteins could occur without concomitant sensitization to common PR-10 from pollen in a subset of subjects. Less commonly recognized PR-10 proteins appear to be an indication of polysensitization.

Electronic supplementary material

The online version of this article (10.1186/s13601-017-0177-4) contains supplementary material, which is available to authorized users.

Debates in allergy medicine: Molecular allergy diagnosis with ISAC will replace screenings by skin prick test in the future

In today's clinical practice patients' skin is used as screening organ for diagnosing type 1 allergy. According to European guidelines skin prick testing with a panel of 18 allergen extracts is recommended, in the US between 10 to 50 allergens are used. The specificity and sensitivity of skin testing is individually highly variable depending on age, body mass, and skin barrier status. In atopic inflammation skin testing gives more false positive results. Smaller skin area and strain limits prick testing in small children. Although the risk for systemic reactions in skin prick testing is very small, emergency medications must be available. Considering the fact that IgE is the only reliable biomarker for type I allergy, upfront IgE screening with ISAC, followed by fewer skin tests to approve positive sensitizations, is proposed. It is time to arrive in the age of molecular allergy diagnosis in daily patient care.

Allergy testing in children with persistent asthma: comparison of four diagnostic methods

BACKGROUND

Multiple allergic sensitizations are common in persistent childhood asthma, and thorough assessment of allergy is crucial for optimal care of these children. Microarray testing offers opportunities for improved sIgE characterization, which has been projected to be useful in the management of multisensitized patients.

OBJECTIVE

The aim of this study was to investigate the accuracy and information obtained by two microarray platforms applied on a well-characterized pediatric asthma cohort.

METHODS

Seventy-one children were recruited from a nationwide Swedish study on severe childhood asthma. Severe (n = 40) and controlled (n = 31) asthmatics were assessed for allergic sensitization by two microarray systems (Microtest and ISAC) and by two standard diagnostic methods (ImmunoCAP and skin prick test). Data on clinical history, physical examination, spirometry, asthma control test, and doctor's diagnosis were collected. Results from the four diagnostic methods were analyzed and compared.

RESULTS

A high prevalence of allergic sensitization was observed in this cohort. The pairwise concordance between two methods was 90-92% independently of methods compared. The sensitivity of the four methods against doctor's diagnosis was 0.77-0.88, and the specificity was 0.97-0.99. Microarray methods provided new information in 47% of the sensitized children in comparison with results obtained by standard diagnostic methods.

CONCLUSION

The high prevalence of food and respiratory sensitization supports the clinical guideline recommendation that allergies should be evaluated in all children with suspected asthma. The microarray platforms studied here demonstrated acceptable accuracy and provided refined IgE characterization in 47% of the patients compared to standard extract-based methods.

Performance evaluation of ImmunoCAP® ISAC 112: a multi-site study

BACKGROUND

After the re-introduction of ImmunoCAP® ISAC sIgE 112 on the market, we undertook a study to evaluate the performance of this multiplex-based immunoassay for IgE measurements to allergen components.

METHODS

The study was carried out at 22 European and one South African site. Microarrays from different batches, eight specific IgE (sIgE) positive, three sIgE negative serum samples and a calibration sample were sent to participating laboratories where assays were performed according to the manufacturer's instructions.

RESULTS

For both the negative and positive samples results were consistent between sites, with a very low frequency of false positive results (0.014%). A similar pattern of results for each of the samples was observed across the 23 sites. Homogeneity analysis of all measurements for each sample were well clustered, indicating good reproducibility; unsupervised hierarchical clustering and classification via random forests, showed clustering of identical samples independent of the assay site. Analysis of raw continuous data confirmed the good accuracy across the study sites; averaged standardized, site-specific ISU-E values fell close to the center of the distribution of measurements from all sites. After outlier filtering, variability across the whole study was estimated at 25.5%, with values of 22%, 27.1% and 22.4% for the 'Low', 'Moderate to High' and 'Very High' concentration categories, respectively.

CONCLUSIONS

The study shows a robust performance of the ImmunoCAP® ISAC 112 immunoassay at different sites. Essentially the same results were obtained irrespective of assay site, laboratory-specific conditions and instruments, operator, or the use of microarrays from different batches.

Microarray Technology Applied to Human Allergic Disease

IgE antibodies serve as the gatekeeper for the release of mediators from sensitized (IgE positive) mast cells and basophils following a relevant allergen exposure which can lead to an immediate-type hypersensitivity (allergic) reaction. Purified recombinant and native allergens were combined in the 1990s with state of the art chip technology to establish the first microarray-based IgE antibody assay. Triplicate spots to over 100 allergenic molecules are immobilized on an amine-activated glass slide to form a single panel multi-allergosorbent assay. Human antibodies, typically of the IgE and IgG isotypes, specific for one or many allergens bind to their respective allergen(s) on the chip. Following removal of unbound serum proteins, bound IgE antibody is detected with a fluorophore-labeled anti-human IgE reagent. The fluorescent profile from the completed slide provides a sensitization profile of an allergic patient which can identify IgE antibodies that bind to structurally similar (cross-reactive) allergen families versus molecules that are unique to a single allergen specificity. Despite its ability to rapidly analyze many IgE antibody specificities in a single simple assay format, the chip-based microarray remains less analytically sensitive and quantitative than its singleplex assay counterpart (ImmunoCAP, Immulite). Microgram per mL quantities of allergen-specific IgG antibody can also complete with nanogram per mL quantities of specific IgE for limited allergen binding sites on the chip. Microarray assays, while not used in clinical immunology laboratories for routine patient IgE antibody testing, will remain an excellent research tool for defining sensitization profiles of populations in epidemiological studies.

Pilot study: assessing the clinical diagnosis of allergy in atopic children using a microarray assay in addition to skin prick testing and serum specific IgE

Background

Children with atopic dermatitis (AD) are at risk of developing allergy. Alongside clinical history, testing modalities include skin prick tests (SPT), specific immunoglobulin-E (sp-IgE) and recently, microarray assays. The aim of this pilot study was to assess current tests and the ISAC sIgE-112 system in the diagnosis of food and aeroallergen allergy.

Methods

Children aged 0–11 years with moderate to severe AD were included. An initial allergy assessment including clinical history, SPT and sp-IgE was performed to determine food and aeroallergen sensitization. A second independent clinical assessment using the same information given to the first assessor and ISAC test results for food and aeroallergen sensitization was also made for each participant. The results from both were compared.

Results

30 children [mean age 3.91 years (SD 3.3)] were included; 53.3 and 46.7 % had moderate and severe AD, respectively. Sp-IgE tests had a higher percentage of positive results compared to SPT and ISAC tests for common allergens. There was a significant difference between the three tests in detecting aeroallergen sensitization (p = 0.038), especially between sp-IgE and ISAC tests, but no significant difference between the tests for food allergen sensitization. There was good agreement between the two assessors; 70 % of the children had a change in diagnosis, with 60 % having at least one diagnosis added and 40 % having at least one diagnosis removed.

Conclusions

There is a role for the use of ISAC testing in diagnosing sensitization and allergy in children with AD as it leads to a change in diagnosis for many patients. Further work is required to assess its clinical and cost effectiveness.

Electronic supplementary material

The online version of this article (doi:10.1186/s12948-016-0046-z) contains supplementary material, which is available to authorized users.

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.

Multiplex component-based allergen microarray in recent clinical studies

During the last decades component-resolved diagnostics either as singleplex or multiplex measurements has been introduced into the field of clinical allergology, providing important information that cannot be obtained from extract-based tests. Here we review recent studies that demonstrate clinical applications of the multiplex microarray technique in the diagnosis and risk assessment of allergic patients, and its usefulness in studies of allergic diseases. The usefulness of ImmunoCAP ISAC has been validated in a wide spectrum of allergic diseases like asthma, allergic rhinoconjunctivitis, atopic dermatitis, eosinophilic esophagitis, food allergy and anaphylaxis. ISAC provides a broad picture of a patient's sensitization profile from a single test, and provides information on specific and cross-reactive sensitizations that facilitate diagnosis, risk assessment, and disease management. Furthermore, it can reveal unexpected sensitizations which may explain anaphylaxis previously categorized as idiopathic and also display for the moment clinically non-relevant sensitizations. ISAC can facilitate a better selection of relevant allergens for immunotherapy compared with extract testing. Microarray technique can visualize the allergic march and molecular spreading in the preclinical stages of allergic diseases, and may indicate that the likelihood of developing symptomatic allergy is associated with specific profiles of sensitization to allergen components. ISAC is shown to be a useful tool in routine allergy diagnostics due to its ability to improve risk assessment, to better select relevant allergens for immunotherapy as well as detecting unknown sensitization. Multiplex component testing is especially suitable for patients with complex symptomatology.

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.

Using Component-Resolved Diagnostics in the Management of Peanut-Allergic Patients

Instead of relying on crude peanut extract, component-resolved diagnostics (CRD) uses sensitization to allergenic proteins within peanut. In this review, we describe the recent advances and future perspectives of the use of CRD in the management of peanut-allergic patients. There is strong evidence that sensitization to Ara h 2 is the best predictor for clinically relevant peanut allergy in children and adults. Isolated sensitization to other peanut components is only rarely present in patients with systemic reactions to peanut. It is, however, important to remark that cut-off points of sIgE to Ara h 2 that predict tolerance or allergy vary between different study populations, different age groups and geographical regions, and validation studies performed in different settings are necessary to implement cut-offs in daily practice. Future studies should focus on the role of CRD in risk-assessment early in life, predicting long-term tolerance and monitoring treatment responses following immunotherapy.

Comparison and clinical utility evaluation of four multiple allergen simultaneous tests including two newly introduced fully automated analyzers

Background

We compared the diagnostic performances of two newly introduced fully automated multiple allergen simultaneous tests (MAST) analyzers with two conventional MAST assays.

Methods

The serum samples from a total of 53 and 104 patients were tested for food panels and inhalant panels, respectively, in four analyzers including AdvanSure AlloScreen (LG Life Science, Korea), AdvanSure Allostation Smart II (LG Life Science), PROTIA Allergy-Q (ProteomeTech, Korea), and RIDA Allergy Screen (R-Biopharm, Germany). We compared not only the total agreement percentages but also positive propensities among four analyzers.

Results

Evaluation of AdvanSure Allostation Smart II as upgraded version of AdvanSure AlloScreen revealed good concordance with total agreement percentages of 93.0% and 92.2% in food and inhalant panel, respectively. Comparisons of AdvanSure Allostation Smart II or PROTIA Allergy-Q with RIDA Allergy Screen also showed good concordance performance with positive propensities of two new analyzers for common allergens (Dermatophagoides farina and Dermatophagoides pteronyssinus). The changes of cut-off level resulted in various total agreement percentage fluctuations among allergens by different analyzers, although current cut-off level of class 2 appeared to be generally suitable.

Conclusions

AdvanSure Allostation Smart II and PROTIA Allergy-Q presented favorable agreement performances with RIDA Allergy Screen, although positive propensities were noticed in common allergens.

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Two new multiple allergen simultaneous tests (MAST) analyzers are evaluated.

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AdvanSure Smart II and PROTIA presented favorable agreement performance with RIDA.

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Positive propensity of new assays for D. farina and D. pteronyssinus was noticed.

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The changes of cut-off level resulted in total agreement percentage fluctuations.