The importance of EN ISO 15189 accreditation of allergen-specific IgE determination for reliable in vitro allergy diagnosis

Molecular allergology: a clinical laboratory tool for precision diagnosis, stratification and follow-up of allergic patients

Identification of the molecular culprits of allergic reactions leveraged molecular allergology applications in clinical laboratory medicine. Molecular allergology shifted the focus from complex, heterogeneous allergenic extracts, e.g. pollen, food, or insect venom, towards genetically and immunologically defined proteins available for in vitro diagnosis. Molecular allergology is a precision medicine approach for the diagnosis, stratification, therapeutic management, follow-up and prognostic evaluation of patients within a large range of allergic diseases. Exclusively available for in vitro diagnosis, molecular allergology is nonredundant with any of the current clinical tools for allergy investigation. As an example of a major application, discrimination of genuine sensitization from allergen cross-reactivity at the molecular level allows the proper targeting of the culprit allergen and thus dramatically improves patient management. This review aims at introducing clinical laboratory specialists to molecular allergology, from the biochemical and genetic bases, through immunological concepts, to daily use in the diagnosis and management of allergic diseases.

Sources of Allergens Detected Through Allergen-Specific Serum IgE Antibody Test in Children with Suspected Allergic Diseases in Central China

Purpose

Although allergic diseases in children are on the rise, there has been no comprehensive investigation of the allergens affecting children with allergic diseases in central China. Therefore, we aimed to analyze the distribution of serum allergen species among children with allergic conditions in central China to inform the prevention, diagnosis, and treatment of childhood allergies.

Patients and Methods

A total of 9213 children (5543 males with 2.88 ± 0.04 years old and 3670 females with 2.91 ± 0.05 years old) underwent allergen screening, and serum allergen-specific IgE (sIgE) antibodies were detected using an automated fluorescent enzyme immunoassay system.

Results

Our findings revealed a total sIgE-positive rate (sIgE-PR) of 57.83%, with mixed food (42.10%), egg whites (30.83%), milk (28.97%), mixed dust mites (24.57%), and mixed molds (23.20%) being the most prevalent source of allergens. The sIgE-PR for common sources of allergens exhibited significant sex-based differences, with males having greater susceptibility than females (p<0.05). Dust mites were the primary source of inhaled allergens, whereas egg white was the predominant source of food allergens. Sources of food allergens were most dominant among infants (0-3 years old); sIgE-PRs for most source of food allergens decreased with age, whereas those for most source of inhaled allergens increased. The autumn sIgE-PRs for mixed molds, weed pollen combinations, and tree pollen combinations were significantly higher than those found in other seasons (p<0.05).

Conclusion

Our findings suggest that sources of allergens profiles in children with allergies vary across age groups and seasons. Understanding these patterns can improve the effective prevention of childhood allergies.

Quantitative Detection of House Dust Mites-Specific IgE by Light-Initiated Chemiluminescence Assay

OBJECTIVE

To establish a new method for quantitative detection of house dust mite (HDM)-sIgE based on light-initiated chemiluminescence assay (LiCA).

METHODS

The assay was established after optimizing the reaction conditions, and the assay performance was evaluated according to the clinical guidelines. Further, the results of LiCA were compared with those from the ELISA and ImmunoCAP methods.

RESULTS

Coefficients of variation for repeatability ranged from 4.22% to 7.69%, and intermediate precision from 8.38% to 10.34%. The limit of blank (LoB), limit of detection (LoD), and limit of quantitation (LoQ) were 0.066 kUA/L, 0.165 kUA/L, and 0.171 kUA/L, respectively. The coefficient of correlation (r) between the results of LiCA and ELISA was 0.9263, and the r between the results of LiCA and ImmunoCAP was 0.8870.

CONCLUSIONS

A HDM-sIgE quantitation assay based on LiCA was established, which could be used as a new reliable analytical tool for the determination of HDM-sIgE.

Evolution Toward Chip-Based Arrays in the Laboratory Diagnosis of Human Allergic Disease

Multiplex-based specific IgE antibody assays have emerged into the clinical immunology laboratory through the combined use of pure, recombinant allergenic molecules and new methods to simultaneously and accurately analyze specific IgE antibodies to hundreds of allergens. This review traces the historical development and examines outstanding questions related to the strengths and limitations of these new molecular allergen multipex technologies for the assessment of human allergic sensitization. Multiplexed technologies are poised to provide the most cost-effective and comprehensive evaluation of patients with suspected allergy as compared with the commonly used singleplex autoanalyzers. How analytically sensitive and quantitative are the multiplex technologies, down to 0.1 kUA/L? Because each allergen is viewed as a unique assay, how will analytical and clinical performance be documented at the manufacturing and clinical laboratory levels to guarantee reproducibility and obtain government regulatory clearance? Will interference by naturally occurring allergen-specific IgG compromise analytical performance? Successful resolution of these and other questions covered in this review will position multiplex technologies to become the single most-effective means of screening patients for allergic sensitization, assessing IgE antibody cross-reactivity, and planning therapy directed at the patient with allergy.

Serological analysis of allergic components of house dust mite provides more insight in epidemiological characteristics and clinical symptom development in North China

Background

House dust mite (HDM) is the most common airborne source causing complex allergy symptoms. There are geographic differences in the allergen molecule sensitization profiles. Serological testing with allergen components may provide more clues for diagnosis and clinical management.

Objective

This study aims to investigate the sensitization profile of eight HDM allergen components in a large number of patients enrolled in the clinic and to analyze the relation of gender, age, and clinical symptoms in North China.

Methods

The 548 serum samples of HDM-allergic patients (ImmunoCAP^® d1 or d2 IgE ≥0.35) were collected in Beijing City and divided in four different age groups and three allergic symptoms. The specific IgE of HDM allergenic components, Der p 1/Der f 1, Der p 2/Der f 2, Der p 7, Der p 10, Der p 21, and Der p 23, was measured using the micro-arrayed allergen test kit developed by Hangzhou Zheda Dixun Biological Gene Engineering Co., Ltd. The new system was validated by comparing to single-component Der p 1, Der p 2, and Der p 23 tests by ImmunoCAP in 39 sera. The epidemiological study of these IgE profiles and the relation to age and clinical phenotypes were analyzed.

Results

A greater proportion of male patients was in the younger age groups, while more female patients were in the adult groups. Both the sIgE levels and the positive rates (approximately 60%) against Der p 1/Der f 1 and Der p 2/Der f 2 were higher than for the Der p 7, Der p 10, and Der p 21 components (below 25%). The Der f 1 and Der p 2 positive rates were higher in 2-12-year-old children. The Der p 2 and Der f 2 IgE levels and positive rates were higher in the allergic rhinitis group. The positive rates of Der p 10 increased significantly with age. Der p 21 is relevant in allergic dermatitis symptom, while Der p 23 contributes to asthma development.

Conclusion

HDM groups 1 and 2 were the major sensitizing allergens, with group 2 being the most important component relevant to respiratory symptoms in North China. The Der p 10 sensitization tends to increase with age. Der p 21 and Der p 23 might be associated with the development of allergic skin disease and asthma, respectively. Multiple allergen sensitizations increased the risk of allergic asthma.

Four clinical phenotypes of cow’s milk protein allergy based on dairy product specific IgE antibody types in North China

Background

Cow’s milk protein allergy (CMPA) is a common allergy. Immunoglobulin E (IgE)-mediated cow’s milk allergy is associated with a high mortality risk and poor prognosis. The study aims to investigate whether there are different clinically CMPA phenotypes in China and to explore the association between CMPA phenotypes and specific IgE (sIgE) antibodies against different dairy products.

Methods

Serum sIgE against different animal milk and cow’s milk products and different milk components was measured by an allergen array. Four CMPA classifications were identified by the presence of serum sIgE: boiled milk-positive, yogurt-positive, buttermilk-positive, and raw milk-positive.

Results

Among the 234 participants included in the study, 9 were boiled milk sIgE-positive, 50 were yogurt sIgE-positive, 17 were buttermilk sIgE-positive, and 158 were only raw milk sIgE-positive. The boiled milk-positive group had the highest levels of raw milk sIgE and casein sIgE antibodies, followed sequentially by the yogurt-positive, buttermilk-positive, and raw milk-positive groups. The boiled milk group observed the highest levels of sIgE against raw milk, casein, α-lactalbumin, and β-lactoglobulin. These levels differed significantly from those in the other three groups. Allergic symptoms were distributed differently among the four study groups. The percentages of allergic patients with gastrointestinal tract symptoms in the above mentioned four groups ranged from high to low, and the percentages of patients with skin symptoms in the four groups ranged from low to high, respectively.

Conclusion

Based on dairy product sIgE antibody levels associated with different milk components and various clinical allergic symptom tendencies, we could distinguish four CMPA phenotypes.

Impact of Preventive Measures on Subjective Symptoms and Antigen Sensitization against Japanese Cedar, Cypress Pollen and House Dust Mites in Patients with Allergic Rhinitis: A Retrospective Analysis in the COVID-19 Era

For >2 years, Japan’s government has been urging the populace to take countermeasures to prevent COVID-19, including mask wearing. We examined whether these preventive behaviors have affected the rate and degree of sensitization against pollen and house dust antigens in patients with allergic rhinitis. We retrospectively surveyed 2565 patients who had undergone allergy blood testing during the period 2015–2021. We subdivided this period into eras based on the COVID-19 pandemic: the pre-COVID (2015–2019, n = 1879) and COVID (2020–2021, n = 686) eras. The positive rates for Japanese cedar and cypress in the 40–59-year-olds and those for house dust in the 20–39-year-olds were significantly reduced in the COVID era versus those in the pre-COVID era. Each group’s mean antigen-specific CAP scores decreased significantly from the 1st to 2nd era: from 1.98 to 1.57 for cedar (p < 0.01), 1.42 to 0.95 for cypress (p < 0.05), and 2.86 to 2.07 for house dust (p < 0.01). Our survey of the patients’ clinical records indicates that 47.5% of the pollinosis patients reported improvement in nasal symptoms after the three seasons of pollen dispersion in the COVID era. Japan’s quarantine policies designed to combat the spread of COVID-19 thus coincide with pivotal measures to alleviate allergic reactions.

A Non-Invasive Neonatal Signature Predicts Later Development of Atopic Diseases

Background: Preterm birth is a major cause of morbidity and mortality in infants and children. Non-invasive methods for screening the neonatal immune status are lacking. Archaea, a prokaryotic life domain, comprise methanogenic species that are part of the neonatal human microbiota and contribute to early immune imprinting. However, they have not yet been characterized in preterm neonates. Objective: To characterize the gut immunological and methanogenic Archaeal (MA) signature in preterm neonates, using the presence or absence of atopic conditions at the age of one year as a clinical endpoint. Methods: Meconium and stool were collected from preterm neonates and used to develop a standardized stool preparation method for the assessment of mediators and cytokines and characterize the qPCR kinetics of gut MA. Analysis addressed the relationship between immunological biomarkers, Archaea abundance, and atopic disease at age one. Results: Immunoglobulin E, tryptase, calprotectin, EDN, cytokines, and MA were detectable in the meconium and later samples. Atopic conditions at age of one year were positively associated with neonatal EDN, IL-1β, IL-10, IL-6, and MA abundance. The latter was negatively associated with neonatal EDN, IL-1β, and IL-6. Conclusions: We report a non-invasive method for establishing a gut immunological and Archaeal signature in preterm neonates, predictive of atopic diseases at the age of one year.

Thermography based skin allergic reaction recognition by convolutional neural networks

In this work we present an automated approach to allergy recognition based on neural networks. Allergic reaction classification is an important task in modern medicine. Currently it is done by humans, which has obvious drawbacks, such as subjectivity in the process. We propose an automated method to classify prick allergic reactions using correlated visible-spectrum and thermal images of a patient’s forearm. We test our model on a real-life dataset of 100 patients (1584 separate allergen injections). Our solution yields good results—0.98 ROC AUC; 0.97 AP; 93.6% accuracy. Additionally, we present a method to segment separate allergen injection areas from the image of the patient’s forearm (multiple injections per forearm). The proposed approach can possibly reduce the time of an examination, while taking into consideration more information than possible by human staff.

Flow Cytometric Analyses of Lymphocyte Markers in Immune Oncology: A Comprehensive Guidance for Validation Practice According to Laws and Standards

Many anticancer therapies such as antibody-based therapies, cellular therapeutics (e.g., genetically modified cells, regulators of cytokine signaling, and signal transduction), and other biologically tailored interventions strongly influence the immune system and require tools for research, diagnosis, and monitoring. In flow cytometry, in vitro diagnostic (IVD) test kits that have been compiled and validated by the manufacturer are not available for all requirements. Laboratories are therefore usually dependent on modifying commercially available assays or, most often, developing them to meet clinical needs. However, both variants must then undergo full validation to fulfill the IVD regulatory requirements. Flow cytometric immunophenotyping is a multiparametric analysis of parameters, some of which have to be repeatedly adjusted; that must be considered when developing specific antibody panels. Careful adjustments of general rules are required to meet legal and regulatory requirements in the analysis of these assays. Here, we describe the relevant regulatory framework for flow cytometry-based assays and describe methods for the introduction of new antibody combinations into routine work including development of performance specifications, validation, and statistical methodology for design and analysis of the experiments. The aim is to increase reliability, efficiency, and auditability after the introduction of in-house-developed flow cytometry assays.

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.

Aspergillus fumigatus in cystic fibrosis: An update on immune interactions and molecular diagnostics in allergic bronchopulmonary aspergillosis

A wide spectrum of pathological conditions may result from the interaction of Aspergillus fumigatus and the immune system of its human host. Allergic bronchopulmonary aspergillosis is one of the most severe A. fumigatus-related diseases due to possible evolution toward pleuropulmonary fibrosis and respiratory failure. Allergic bronchopulmonary aspergillosis occurs almost exclusively in cystic fibrosis or asthmatic patients. An estimated 8%-10% of patients with cystic fibrosis experience this condition. The diagnosis of allergic bronchopulmonary aspergillosis relies on criteria first established in 1977. Progress in the understanding of host-pathogen interactions in A. fumigatus and patients with cystic fibrosis and the ongoing validation of novel laboratory tools concur to update and improve the diagnosis of allergic bronchopulmonary aspergillosis.

Allergy Testing and Drug Screening on an ITO-Coated Lab-on-a-Disc

A lab-on-a-disc (LOAD) is a centrifugal microfluidic set-up based on centrifugal force without using micro-pumps to drive reagents and cells to various chambers through channels and valves for reactions. A LOAD coated with conductive transparent indium tin oxide (ITO) for thermal control was developed to screen allergy-blocking agents. When the acridine orange (AO)-loaded KU-812 human basophilic cells were activated in the LOAD by stimuli, AO trapped in the cytoplasmic granules was released externally as an allergic mediator mimetic to report degranulation. This response was monitored by fluorescence when the released AO in supernatant had been transferred, with a higher spinning speed, from the reaction chamber to detection chamber in the LOAD where AO reacted with exogenous DNA. We report here the principles of the system and an improved LOAD set-up with the ITO-coated glass resistive microheater to run assays at 37 °C. By using this platform, we demonstrate here for the first time that triptolide, an active ingredient from the Chinese medicine herb Tripterygium wilfordii Hook f., was able to suppress the fMLP-mediated degranulation in basophils. This serves as an example how LOADs can be used to screen agents to alleviate symptoms of allergy.

Quality management in IgE-based allergy diagnostics

Assays for total and allergen-specific (s) IgE are essential serological tests in the diagnostic work-up of immediate type hypersensitivity reactions and atopic diseases. Technical performance characteristics and clinical utility of IgE tests have been published in international guidelines. In the USA and in Europe, IgE tests are mainly performed by accredited medical laboratories and in Germany they are also performed by allergists carrying an OIII-limited license. Both have to perform continuously internal and external quality control measures including proficiency trials twice a year (in Germany). Due to the heterogeneity of the assay’s core allergen reagents, complex extracts and more recently defined allergenic molecules, and heterologous assay calibration, the results of qualitative and quantitative sIgE tests from different diagnostic manufacturers can vary considerably. Proficiency trial results are subsequently grouped according to each assay type. Passing acceptance criteria depend on national rules and regarding quality management. Future challenges include a more valid quantification of sIgE which would allow true comparisons with the international units for total IgE, and the use of harmonized allergen reagents for the most important allergen sources, which have hampered inter-assay comparability in the past.

Determinants of venom-specific IgE antibody concentration during long-term wasp venom immunotherapy

Background

Venom immunotherapy (VIT) is an effective treatment for subjects with systemic allergic reactions (SR) to Hymenoptera stings, however there are few studies concerning the relevance of the venom specific IgE changes to decide about VIT cessation. We assessed IgE changes during a 5-year VIT, in patients stung and protected within the first 3 years (SP 0–3) or in the last 2 years (SP 3–5), and in patients not stung (NoS), to evaluate possible correlations between IgE changes and clinical protection.

Methods

Yellow jacket venom (YJV)-allergic patients who completed 5 years of VIT were retrospectively evaluated. Baseline IgE levels and after the 3rd and the 5th year of VIT were determined; all patients were asked about field stings and SRs.

Results

A total of 232 YJV-allergic patients were included and divided into the following groups: 84 NoS, 72 SP 0–3 and 76 SP 3–5. IgE levels decreased during VIT compared to baseline values (χ² = 346.029, p < 0.001). Recent vespid stings accounted for significantly higher IgE levels despite clinical protection. IgE levels after 5 years of VIT correlated significantly with Mueller grade (F = 2.778, p = 0.012) and age (F = 6.672, p = 0.002). During follow-up from 1 to 10 years after VIT discontinuation, 35.2 % of the contacted patients reported at least one field sting without SR.

Conclusions

The yellow jacket-VIT temporal stopping criterion of 5 years duration did not result in undetectable IgE levels, despite a long-lasting protection. A mean IgE decrease from 58 to 70 % was observed, and it was less marked in elderly patients or in subjects with higher Mueller grade SR.