Exploring the temporal development of childhood IgE profiles to allergen components

Allergic sensitization to lipocalins reflects asthma morbidity in dog dander sensitized children

Background

Sensitization to dog is an important risk factor for asthma in children, but the clinical relevance of IgE to available dog‐ and furry animal allergen molecules is uncertain.

Methods

Spirometry, methacholine challenge, fraction of exhaled nitric oxide, nasal challenge with dog extract and questionnaires were performed in 59 dog‐sensitized children (age 10–18 years). Serum IgE to dog‐, cat‐, horse extracts and the allergen molecules Can f 1–6, Fel d 1, Fel d 2, Fel d 4 and Equ c 1 were evaluated.

Results

Median numbers of positive IgE results to furry animal allergen molecules among children without asthma was 3, with asthma 5.5 and with troublesome asthma 9 (asthma vs. no asthma; p = 0.039; troublesome asthma vs. no asthma; p = 0.009). The odds ratio for asthma if sensitized to any lipocalin was 7.2 (95% confidence Interval: 1.44–35.9). Children with troublesome asthma had higher IgE levels to the lipocalins Can f 2, Can f 4 and Can f 6 compared to the rest of the study population (44 vs. 4.1 kU_A/L, p = 0.015; 5.8 vs. 0.9 kU_A/L, p = 0.018 and 1.3 vs. 0.7 kU_A/L, p = 0.03 respectively). Furthermore, a positive nasal challenge was more common among children with troublesome asthma (83% vs. 36%, p = 0.036).

Conclusions

Polysensitization to furry animal allergens and lipocalins is associated with asthma in dog‐sensitized children. Children with troublesome asthma have higher IgE levels to several dog lipocalins than other dog sensitized children.

Key message

Polysensitization to furry animal allergens and high IgE levels to the dog lipocalins Can f 2, Can f 4 and Can f 6 is associated with asthma severity in dog dander sensitized children. Molecular allergy diagnostics may thus help the clinicians to evaluate the impact of allergic sensitization on asthma morbidity.

Patterns of sensitization to inhalant and food allergens among pediatric patients from the Moscow region (Russian Federation)

The immunological profiles of human specific IgE (sIgE) and specific IgG4 (sIgG4) vary by genetic predisposition, living conditions in different geographical locations and patient’s age. The aim of our study was to analyze sIgE and sIgG4 patterns and their age-dependent changes in patients from the Moscow region. For identifying sIgE and sIgG4 profiles the blood samples from 513 patients aged 6 months to 17 years who were showing symptoms of allergic diseases were analyzed using microarrays containing 31 allergens. The highest sIgE prevalence was observed for birch pollen (32%) among pollen allergens, cat dander (24%) among indoor allergens, and egg whites (21%) among food allergens. The most common sIgG4 response was developed toward egg whites (80% of patients). Age-related elevation was identified for patients with increased sIgE to pollen allergens and indoor allergens (cat or dog dander and house dust mites). For each allergen, the proportion of cases with significant levels of sIgG4 appeared to increase with patients’ age. The data on allergen-specific sIgE and sIgG4 prevalence show both general trends and some local special aspects that are indicative for the Moscow region. This information should be useful in terms of epidemiology of allergic diseases.

ImmunoCAP® ISAC and Microtest for multiplex allergen testing in people with difficult to manage allergic disease: a systematic review and cost analysis

BACKGROUND

Allergy is a form of immune-mediated exaggerated sensitivity (hypersensitivity) to a substance that is either inhaled, swallowed, injected or comes into contact with the skin. Foreign substances that provoke allergies are called allergens. It has been claimed that multiplex allergen testing may help in diagnosing the cause of symptoms in patients with an unclear cause of allergy or who are allergic to more than one substance.

OBJECTIVES

To evaluate multiplex allergen testing [devices that can measure the presence of multiple immunoglobulin E (IgE) antibodies in a patient's blood at the same time], by assessing (1) clinical effectiveness (allergy symptoms, incidence of acute exacerbations, mortality, adverse events of testing and treatment, health-care presentations or admissions, health-related quality of life); (2) effects on treatment (diet, immunotherapy medications, other potential testing); (3) any additional diagnostic information provided by multiplex allergen testing; and (4) cost-effectiveness (cost of different assessment strategies).

METHODS

Fifteen databases were searched from 2005 to April 2015, including MEDLINE (via OvidSp), MEDLINE In-Process Citations, MEDLINE Daily Update, PubMed (National Library of Medicine), EMBASE, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), Database of Abstracts of Reviews of Effects (DARE), Health Technology Assessment (HTA) database, Science Citation Index (SCI), Conference Proceedings Citation Index-Science (CPCI-S), BIOSIS Previews, Latin American and Caribbean Health Sciences Literature (LILACS), National Institute for Health Research (NIHR) HTA programme, and the US Food and Drug Administration (FDA); supplementary searches of conference proceedings and trials registries were performed. Review methods followed published guidance from the Cochrane Collaboration and the Centre for Reviews and Dissemination, University of York, UK. The methodological quality of included studies was assessed using appropriate published tools or a review-specific tool designed by the project team. Studies were summarised in a narrative synthesis. Owing to a lack of data on the clinical effectiveness of multiplex allergen testing, no long-term cost-effectiveness model was developed. A conceptual model structure was developed and cost analyses were performed to examine the short-term costs of various possible diagnostic pathways.

RESULTS

Fifteen studies were included in the review. The very limited available data indicated that the addition of multiplex allergen testing [ImmunoCAP(®) Immuno Solid-phase Allergen Chip (ISAC), Thermo Fisher Scientific/Phadia AB, Uppsala, Sweden] to standard diagnostic work-up can change the clinicians' views on the diagnosis, management and treatment of patients. There was some indication that the use of ImmunoCAP ISAC testing may be useful to guide decisions on the discontinuation of restrictive diets, the content of allergen-specific immunotherapy (SIT) prescriptions, and whether or not patients should receive SIT. However, none of the studies that we identified reported any information on clinical outcomes subsequent to changes in treatment or management. There was some evidence that ImmunoCAP ISAC may be useful for discriminating allergens that are structurally similar and are recognised by the same IgE antibody (cross-immunoreactive). No data were available for Microtest (Microtest Matrices Ltd, London, UK). Detailed cost analyses suggested that multiplex allergen testing would have to result in a substantial reduction of the proportions of patients receiving single IgE testing and oral food challenge tests in order to be cost-saving in the short term.

CONCLUSIONS

No recommendations for service provision can be made based on the analyses included in this report. It is suggested that a consensus-based protocol for the use of multiplex allergen testing be developed. The clinical effectiveness and cost-effectiveness of the proposed protocol should then be assessed by comparing long-term clinical and quality of life outcomes and resource use in patients managed using the protocol with those managed using a standard diagnostic pathway.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015019739.

FUNDING

This project was a Diagnostic Assessment Report commissioned by the NIHR HTA programme on behalf of the National Institute for Health and Care Excellence.

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.

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.

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

Microarray platforms, enabling simultaneous measurement of many allergens with a small serum sample, are potentially powerful tools in allergy diagnostics. We report here the first study comparing a fully automated microarray system, the Microtest allergy system, with a manual microarray platform, Immuno-Solid phase Allergen Chip (ISAC), and two well-established singleplex allergy tests, skin prick test (SPT) and ImmunoCAP, all tested on the same patients. One hundred and three adult allergic patients attending the allergy clinic were included into the study. All patients were tested with four allergy test methods (SPT, ImmunoCAP, Microtest and ISAC 112) and a total of 3485 pairwise test results were analysed and compared. The four methods showed comparable results with a positive/negative agreement of 81-88% for any pair of test methods compared, which is in line with data in the literature. The most prevalent allergens (cat, dog, mite, timothy, birch and peanut) and their individual allergen components revealed an agreement between methods with correlation coefficients between 0·73 and 0·95. All four methods revealed deviating individual patient results for a minority of patients. These results indicate that microarray platforms are efficient and useful tools to characterize the specific immunoglobulin (Ig)E profile of allergic patients using a small volume of serum sample. The results produced by the Microtest system were in agreement with diagnostic tests in current use. Further data collection and evaluation are needed for other populations, geographical regions and allergens.

A population-based study of animal component sensitization, asthma, and rhinitis in schoolchildren

BACKGROUND

Animal sensitization is a major determinant of asthma in children. Component-resolved studies of unselected pediatric populations are lacking. The aim was to describe sensitization to animal components and the association with asthma and rhinitis in animal-sensitized schoolchildren.

METHODS

A random sample of 696 children (11-12 years) from a Swedish population-based cohort was tested for sensitization to cat, dog, and horse dander using ImmunoCAP. Sera from animal-sensitized children were further analyzed by microarray including three allergen components from cat, four from dog, and two from horse. The parents completed an expanded ISAAC questionnaire.

RESULTS

Of 259 animal-sensitized children (≥0.1 kUA /l), 51% were sensitized to all three, 23% to two, and 25% to one species. Current asthma and asthma symptoms following contact with cats were associated with co-sensitization to Fel d 1 and Fel d 4. This association was seen already at moderate-level sensitization (1-15 ISU) to Fel d 4, at which level most children were sensitized to Fel d 1, as well. In dog-sensitized children, the majority was sensitized to more than one dog component, and co-sensitization to Can f 5 and Can f 1/f 2 conferred the greatest risk for asthma. Sensitization to the highly cross-reactive serum albumins was uncommon and not associated with asthma.

CONCLUSIONS

Among schoolchildren in northern Sweden, where mite allergy is uncommon, furry animals were the primary perennial sensitizers. Asthma was associated with higher levels of component sensitization, and sensitization to more than one component from the same animal conferred the greatest risk.

The use of the MeDALL-chip to assess IgE sensitization: a new diagnostic tool for allergic disease?

BACKGROUND

Allergic sensitization is frequently present in asthma and rhinitis, but the role of specific immunoglobulin E (s-IgE) is not always clear. Multiple s-IgE analyses may provide insight into this relationship, thus a microarray chip was developed within the EU-funded MeDALL project. The main objective was to evaluate the performance of the MeDALL-chip compared to ImmunoCAP and skin prick test (SPT) in detecting allergic sensitization in children and secondarily to investigate the association to asthma and allergic rhinitis.

METHODS

From the 'Environment and Childhood Asthma Study', 265 children were investigated at 10 and 16 yr of age with clinical examination, interview, SPT, ImmunoCAP, and the MeDALL-chip including 152 allergen components in the analysis.

RESULTS

Allergic sensitization at 10 yr was more frequently detected using the MeDALL-chip (38.1%) compared to the ImmunoCAP (32.8%) (p = 0.034) and SPT (25.5%) (p < 0.001), but no significant difference was seen at 16 yr (MeDALL-chip 49.8%, ImmunoCAP 48.6%, SPT 45.8%). The MeDALL-chip did not differ significantly from the ImmunoCAP or SPT in terms of detecting allergic sensitization in subjects with rhinitis or asthma at 10 or 16 yr.

CONCLUSION

The prevalence of allergic sensitization increased by all three diagnostic tests from 10 to 16 yr was similar by SPT and ImmunoCAP and significantly higher with the MeDALL-chip at 10 yr. All three tests were comparable for identification of allergic sensitization among children with current rhinitis or asthma.

ELISA in the multiplex era: potentials and pitfalls

Multiplex immunoassays confer several advantages over widely adopted singleplex immunoassays including increased efficiency at a reduced expense, greater output per sample volume ratios and higher throughput predicating more resolute, detailed diagnostics and facilitating personalised medicine. Nonetheless, to date, relatively few protein multiplex immunoassays have been validated for in vitro diagnostics in clinical/point-of-care settings. This review article will outline the challenges, which must be ameliorated prior to the widespread integration of multiplex immunoassays in clinical settings: (i) biomarker validation; (ii) standardisation of immunoassay design and quality control (calibration and quantification); (iii) availability, stability, specificity and cross-reactivity of reagents; (iv) assay automation and the use of validated algorithms for transformation of raw data into diagnostic results. A compendium of multiplex immunoassays applicable to in vitro diagnostics and a summary of the diagnostic products currently available commercially are included, along with an analysis of the relative states of development for each format (namely planar slide based, suspension and planar/microtitre plate based) with respect to the aforementioned issues.

Novel in silico technology in combination with microarrays: a state-of-the-art technology for allergy diagnosis and management?

'Allergen microarrays, in poly-sensitized allergic patients, represent a real value added in the accurate IgE profiling and in the identification of allergen(s) to administer for an effective allergen immunotherapy.' Allergen microarrays (AMA) were developed in the early 2000s to improve the diagnostic pathway of patients with allergic reactions. Nowadays, AMA are constituted by more than 100 different components (either purified or recombinant), representing genuine and cross-reacting molecules from plants and animals. The cost of the procedure had suggested its use as third-level diagnostics (following in vivo- and in vitro-specific IgE tests) in poly-sensitized patients. The complexity of the interpretation had inspired the development of in silico technologies to help clinicians in their work. Both machine learning techniques and expert systems are now available. In particular, an expert system that has been recently developed not only identifies positive and negative components but also lists dangerous components and classifies patients based on their potential responsiveness to allergen immunotherapy, on the basis of published algorithms. For these characteristics, AMA represents the state-of-the-art technology for allergy diagnosis in poly-sensitized patients.

Tus-Ter-lock immuno-PCR assays for the sensitive detection of tropomyosin-specific IgE antibodies

BACKGROUND

The increasing prevalence of food allergies requires development of specific and sensitive tests capable of identifying the allergen responsible for the disease. The development of serologic tests that can detect specific IgE antibodies to allergenic proteins would, therefore, be highly received.

RESULTS

Here we present two new quantitative immuno-PCR assays for the sensitive detection of antibodies specific to the shrimp allergen tropomyosin. Both assays are based on the self-assembling Tus-Ter-lock protein-DNA conjugation system. Significantly elevated levels of tropomyosin-specific IgE were detected in sera from patients allergic to shrimp.

CONCLUSION

This is the first time an allergenic protein has been fused with Tus to enable specific IgE antibody detection in human sera by quantitative immuno-PCR.

Advances in allergen-microarray technology for diagnosis and monitoring of allergy: the MeDALL allergen-chip

Allergy diagnosis based on purified allergen molecules provides detailed information regarding the individual sensitization profile of allergic patients, allows monitoring of the development of allergic disease and of the effect of therapies on the immune response to individual allergen molecules. Allergen microarrays contain a large variety of allergen molecules and thus allow the simultaneous detection of allergic patients' antibody reactivity profiles towards each of the allergen molecules with only minute amounts of serum. In this article we summarize recent progress in the field of allergen microarray technology and introduce the MeDALL allergen-chip which has been developed for the specific and sensitive monitoring of IgE and IgG reactivity profiles towards more than 170 allergen molecules in sera collected in European birth cohorts. MeDALL is a European research program in which allergen microarray technology is used for the monitoring of the development of allergic disease in childhood, to draw a geographic map of the recognition of clinically relevant allergens in different populations and to establish reactivity profiles which are associated with and predict certain disease manifestations. We describe technical advances of the MeDALL allergen-chip regarding specificity, sensitivity and its ability to deliver test results which are close to in vivo reactivity. In addition, the usefulness and numerous advantages of allergen microarrays for allergy research, refined allergy diagnosis, monitoring of disease, of the effects of therapies, for improving the prescription of specific immunotherapy and for prevention are discussed.

Severe childhood asthma and allergy to furry animals: refined assessment using molecular-based allergy diagnostics

BACKGROUND

Allergy to cats and dogs and polysensitization towards these animals are associated with severe childhood asthma. Molecular-based allergy diagnostics offers new opportunities for improved characterization and has been suggested to be particularly useful in patients with polysensitization and/or severe asthma. The aim was to use extract- and molecular-based allergy diagnostics to compare patterns of IgE sensitization towards aeroallergens in children with problematic severe and controlled asthma.

METHODS

Children with a positive ImmunoCAP towards any furry animal (cat, dog or horse) were recruited from a Nationwide Swedish study on severe childhood asthma. Severe (n = 37, age 13 years) and controlled (n = 28, age 14 years) asthmatics underwent assessment of allergic sensitization by ImmunoCap (kUA /l) and immunosolid-phase allergen chip (ISAC). In addition, Asthma Control Test, spirometry and a methacholine challenge were performed.

RESULTS

Children with severe asthma had lower asthma control (p < 0.001) and FEV1 (p = 0.001) and more bronchial hyper-responsiveness (p = 0.008) in spite of high doses of inhaled steroids (≥800 μg budesonide). Children with severe asthma displayed higher levels of IgE antibodies towards cat (17 vs. 3.9, p = 0.027), dog (3.8 vs. 1.2, p = 0.012) and horse (7.4 vs. 0.7, p = 0.014). Sensitization towards Can f 2 (22% vs. 0%, p = 0.009) and Equ c 1 (51% vs. 25%, p = 0.03) was more common in severe asthma. IgE levels towards Equ c 1 correlated with asthma control (r = -0.41, p = 0.04).

CONCLUSION

Children with severe allergic asthma had higher sIgE levels to cat, dog and horse. Molecular-based allergy diagnostics revealed a more complex molecular spreading of allergen components in children with the most severe disease.

A WAO - ARIA - GA²LEN consensus document on molecular-based allergy diagnostics

Molecular-based allergy (MA) diagnostics is an approach used to map the allergen sensitization of a patient at a molecular level, using purified natural or recombinant allergenic molecules (allergen components) instead of allergen extracts. Since its introduction, MA diagnostics has increasingly entered routine care, with currently more than 130 allergenic molecules commercially available for in vitro specific IgE (sIgE) testing.

MA diagnostics allows for an increased accuracy in allergy diagnosis and prognosis and plays an important role in three key aspects of allergy diagnosis: (1) resolving genuine versus cross-reactive sensitization in poly-sensitized patients, thereby improving the understanding of triggering allergens; (2) assessing, in selected cases, the risk of severe, systemic versus mild, local reactions in food allergy, thereby reducing unnecessary anxiety for the patient and the need for food challenge testing; and (3) identifying patients and triggering allergens for specific immunotherapy (SIT).

Singleplex and multiplex measurement platforms are available for MA diagnostics. The Immuno-Solid phase Allergen Chip (ISAC) is the most comprehensive platform currently available, which involves a biochip technology to measure sIgE antibodies against more than one hundred allergenic molecules in a single assay. As the field of MA diagnostics advances, future work needs to focus on large-scale, population-based studies involving practical applications, elucidation and expansion of additional allergenic molecules, and support for appropriate test interpretation. With the rapidly expanding evidence-base for MA diagnosis, there is a need for allergists to keep abreast of the latest information. The aim of this consensus document is to provide a practical guide for the indications, determination, and interpretation of MA diagnostics for clinicians trained in allergology.