Performance of the PROTIA™ Allergy-Q® System in the Detection of Allergen-specific IgE: A Comparison With the ImmunoCAP® System

Glutamine and lysine as common residues from epitopes on α-lactalbumin and β-lactoglobulin from cow milk identified by phage display technology

Cow milk is an important source of food protein for children; however, it could lead to allergy, especially for infants. α-Lactalbumin (α-LA) and β-lactoglobulin (β-LG) from whey protein make up a relatively high proportion of milk proteins and have received widespread attention as major allergens in milk. However, few studies have identified the epitopes of both proteins simultaneously. In this study, ImmunoCAP and indirect ELISA were first used for detection of sIgE to screen sera from allergic patients with high binding capacity for α-LA and β-LG. Subsequently, the mimotopes was biopanned by phage display technology and bioinformatics and 17 mimic peptide sequences were obtained. Aligned with the sequences of α-LA or β-LG, we identified one linear epitope on α-LA at AA 11-26 and 5 linear epitopes on β-LG at AA 9-29, AA 45-57, AA 77-80, AA 98-101, and AA 121-135, respectively. Meanwhile, the 8 conformational epitopes and their distributions of α-LA and β-LG were located using the Pepitope Server. Finally, glutamine and lysine were determined as common AA residues for the conformational epitopes both on α-LA and β-LG. Moreover, we found the addition of mouse anti-human IgE during the biopanning process did not significantly affect the identification of the epitopes.

KOREAN AEROALLERGEN SENSITIZATION STATUS FROM 2018-2021

Objectives.

Studies on the aeroallergen sensitization status of South Koreans based on large-scale data are lacking.

Methods.

We analyzed data from 368,156 multiple allergosorbent tests collected by a domestic medical diagnosis company from 3,735 hospitals nationwide from 2018 to 2021. We additionally collected sex, age, and regional data. If the level of an aeroallergen was 0.35 IU/mL or more, the test result for that aeroallergen was defined as positive, and positive cases were defined as those where one aeroallergen was positive. The positive ratio (PR) for aeroallergens was calculated using positive cases.

Results.

In total, 347,996 cases were analyzed, excluding cases with missing data. The percentage of positive cases was 56.7%, which was highest in adolescents (74.1%) and lowest in the elderly (47.0%). All four types of mites had high PRs (0.382–0.655), and mold had low PRs (0.023–0.058). Among pollens, the PRs of grasses were generally high (more than 0.14), followed by weeds (approximately 0.10), and the PRs of woods was less than 0.1. For animals, cats and dogs had the highest PRs, at 0.231 and 0.183, respectively. The value for cockroaches was also high, at 0.211. The PRs of indoor aeroallergens, such as mites, molds, and animals, were high in adolescents, and those of pollen and cockroaches were high in the elderly. In Jeju, the PR of Japanese cedars was extremely high (0.222).

Conclusion.

Koreans were found to be sensitized to a wide variety of aeroallergens. There were significant differences in sensitization patterns according to age and region.

Inter-laboratory comparison of semiquantitative allergen-specific Immunoglobulin E test: 7 years of experience in Korea

INTRODUCTION

Multiple allergen simultaneous test (MAST) is widely used as a screening tool for allergic diseases and has the advantage of providing specific IgE (sIgE) results for various allergens in semiquantitative class. We have continuously conducted external quality assessment (EQA) since 2012 for clinical laboratories performing MAST using AdvanSure allergy screen test (LG CHEM, Korea). This study provides an account of the EQA experience.

METHODS

Samples were prepared using pooled sera collected from patients with suspected allergic disease and sent to each laboratory twice a year. Each round included 4-6 serum samples with sIgE for 10-20 inhaled or food allergens. The acceptable class value was the most frequently reported MAST class ±1 titer that exceeded 80% of the total laboratory results.

RESULTS

The average number of participating laboratories was 76 (49-90) and the average response rate was 97.3% during the entire survey period. The acceptable rates were consistently high at 97.7% ± 3.7%. Of the total 537 trials, 18 trials (3.4%) were regarded as nonconsensus results, in which acceptable answers did not exceed 80%. For unacceptable results, the false-negative rate (1.5% ± 2.8%) was higher than the false-positive rate (0.8% ± 2.7%) (p < 0.001). MAST class results were correlated with quantitative IgE results by ImmunoCAP (Spearman's correlation coefficient of 0.682 (p < 0.001) and gamma index of 0.777 (p < 0.001).

CONCLUSION

Although EQA for MAST showed a high level of acceptable answer, some allergen assays require harmonization. Continuous performance of systematic EQA is needed to improve the accuracy of sIgE assays and quality control in clinical laboratories.

Prediction of Food Allergens Sensitization Based on History Taking Technique in Young Children

BACKGROUND

The diagnosis of food allergies needs to be confirmed through an oral food challenge (OFC). However, specific immunoglobulin E (sIgE) concentrations analyzed by serological tests are also helpful in determining OFC items and predicting the presence of allergic reactions. Unfortunately, there is a limit to the number of antigens that can be simultaneously evaluated at one time. The purpose of this study was to analyze the possibility of detecting sIgE antibodies against food using clues in self-reported food allergy symptoms.

METHODS

Medical records of 377 patients aged 3 years or younger were collected for egg white-, cow's milk-, walnut- and soybean-sIgE sensitization, and related clinical history. Each clinical history was classified into class 1: direct-isolated intake resulting in anaphylaxis or hives with consistent clincical history; class 2a: class 1 with inconsistency; class 2b: indirect-mixed intake resulting in anaphylaxis or hives regardless of consistency; class 2c: direct/indirect-isolated/mixed intake resulting in itching without hives, vomiting, or diarrhea with consistent clincical history; or class 3: class 2c with inconsistency or asymptomatic to direct, isolated exposure.

RESULTS

The area under the curve (AUC) of class 1 for cow's milk was 0.790, and the accuracy was 78.0%. The AUC of class 1 and 2 for egg white was better than that of class 1 (0.750), and the accuracy rate was 77.6%. The AUCs of class 1 for walnut and soybean were 0.775 and 0.662, respectively.

CONCLUSION

In conclusion, sIgE sensitization to foods could be predicted by the combination of exposure and selfreported symptoms in children under 3 years of age.

Proyecto VALIDA: Validation of ALlergy In vitro Diagnostics Assays (Herramientas y recomendaciones para la valoración de las pruebas in vitro en el diagnóstico de la alergia)

En la evaluación del paciente con sospecha de alergia las pruebas de detección y cuantificación de la inmunoglobulina E (IgE) específica in vitro se usan de manera habitual en los laboratorios clínicos para ayudar en el diagnóstico de la alergia. Actualmente existen diferentes alternativas comerciales para realizar estos ensayos, pero los resultados obtenidos por cada uno de ellos pueden variar, lo que condiciona el diagnóstico y el tratamiento que se le proporcionará al paciente. Con el fin de dar respuesta a los retos planteados por las diferencias entre las distintas técnicas para la determinación in vitro de la IgE específica, un grupo de expertos ha recogido en un documento una serie de recomendaciones sobre las implicaciones que puede tener el uso de una determinada técnica in vitro y el impacto en el manejo del paciente alérgico que suponen las diferencias entre las distintas técnicas. La lectura y el análisis de este documento de consenso ayudarán a entender las implicaciones que tiene el cambio de método de diagnóstico in vitro en el manejo del paciente con alergia, en su calidad de vida y en los costes socioeconómicos asociados a la enfermedad.

VALIDA project: Validation of allergy in vitro diagnostics assays (Tools and recommendations for the assessment of in vitro tests in the diagnosis of allergy)

In vitro allergen-specific immunoglobulin E (IgE) detection and quantification tests are routinely performed in clinical laboratories to diagnose patients with a suspected allergy. Numerous commercial assays are available to test for allergies, but the results can vary widely, thereby influencing both diagnosis and treatment. Given the challenges posed by differences in the various assays for in vitro determination of specific IgE, a group of experts has compiled in a document a series of recommendations on the implications that the use of a certain in vitro technique may have and the impact on the management of the allergic patient that the differences between the various techniques represent. The reading and analysis of this consensus document will help to understand the implications of the change of in vitro diagnostic method in the management of the patient with allergy, in the quality of life and in the socioeconomic costs associated with the disease.

Validation of PROTIA™ Allergy-Q 64 Atopy® as a Specific IgE Measurement Assay for 10 Major Allergen Components

PURPOSE

Component-resolved diagnostics (CRD) is expected to provide additional diagnostic information in allergic patients. PROTIA™ Allergy-Q 64 Atopy®, a recently developed CRD-based multiplex specific immunoglobulin E (sIgE) assay, can quantitatively measure sIgE to major allergen components.

METHODS

The sIgE detection by PROTIA™ Allergy-Q 64 Atopy® and ImmunoCAP® assays was compared using the sera of 125 Korean allergic patients. Group 1 and 2 allergens of house dust mites (HDMs; Dermatophagoides farinae (Der f) 1 and Der f 2 in PROTIA™ Allergy-Q 64 Atopy®, Dermatophagoides pteronyssinus (Der p) 1 and Der p 2 in ImmunoCAP®), Bet v 1, Fel d 1, Que a 1, ω-5 gliadin, α-lactalbumin, β-lactoglobulin, casein and α-Gal were measured by both assays.

RESULTS

Comparing the results from the 2 assays, the agreement rate for all the 10 allergens was > 88% (group 1 HDM allergen, 100%; group 2 HDM allergen, 94.6%; Bet v 1, 97.4%; Fel d 1, 90.5%; Que a 1, 89.2%; α-lactalbumin, 96%; β-lactoglobulin, 88%; casein, 88%; ω-5 gliadin, 96%; α-Gal, 100%). Correlation analysis indicated that, all the 10 allergen sIgEs showed more than moderate positive correlation (Pearson correlation coefficients > 0.640). Additionally, intra-class comparison showed more than high correlation for all the 10 allergens (Spearman's rank correlation coefficients > 0.743).

CONCLUSIONS

PROTIA™ Allergy-Q 64 Atopy® is reliable and comparable to the ImmunoCAP® assay for component-resolved diagnosis.

Comparison of Singleplex Specific IgE Detection Immunoassays: ImmunoCAP Phadia 250 and Immulite 2000 3gAllergy

BACKGROUND

The identification of clinically meaningful specific immunoglobulin E (sIgE) is important for the diagnosis and management of allergic diseases. Various in vitro sIgE detection methods are available worldwide. Depending on the number of antigens that can be tested simultaneously, there are two representative methods: singleplex and multiplex. Singleplex sIgE detection is mainly provided by Thermo Fisher (ImmunoCAP) and Siemens (Immulite). This study aimed to compare the diagnostic agreement of two singleplex sIgE detection assays.

METHODS

Sera from 209 Korean patients with allergic disease were used to compare the ImmunoCAP and Immulite assays with respect to the following allergens: inhalant allergens (Dermatophagoides farinae, cat and dog dander, oak, rye grass, mugwort, Alternaria, German cockroach) and food allergens (hen's egg white, cow's milk, wheat, peanut, soybean, and shrimp). Data from 902 paired comparison tests were included for comparisons. Qualitative, semi-quantitative, and quantitative comparisons were performed using statistical analyses.

RESULTS

In qualitative comparisons, the positivity and negativity agreements ranged from 75% (wheat, shrimp) to 96% (Alternaria). Class consistency (classes 0-6) was well matched. Spearman's rank correlation coefficients for all allergens except shrimp were over 0.7. In quantitative comparisons, all allergens excluding shrimp showed >0.7 intra-class correlation coefficients.

CONCLUSIONS

The ImmunoCAP and Immulite systems showed similar performances. However, clinicians should consider fundamental methodological differences between the assays.

Comparison of the ImmunoCAP Assay and AdvanSure™ AlloScreen Advanced Multiplex Specific IgE Detection Assay

PURPOSE

The AdvanSure™ AlloScreen assay is an advanced multiplex test that allows for simultaneous detection of specific IgE (sIgE) against multiple allergens. For precise identification of causative allergens in allergic patients, we compared this new multiplex sIgE assay with the ImmunoCAP assay, which is currently the gold-standard method for sIgE detection.

MATERIALS AND METHODS

Serum samples from 218 Korean allergic disease patients were used to compare the ImmunoCAP and AlloScreen assays with respect to the following 13 allergens: Dermatophagoides pteronyssinus, Dermatophagoides farinae, cat and dog dander, Alternaria, birch, oak, ragweed, mugwort, rye grass, and food allergens (egg white, cow's milk, peanuts).

RESULTS

A total of 957 paired tests using the 13 allergens were compared. The total agreement ratio ranged from 0.74 (oak) to 0.97 (Alternaria). With respect to class association analyses, the gamma index ranged from 0.819 (rye grass) to 0.990 (Alternaria). The intra-class correlation coefficients for house dust mites, cat and dog dander, Alternaria, birch, ragweed, egg white, cow's milk, and peanut sIgE titers were >0.8.

CONCLUSION

The AlloScreen and ImmunoCAP assays exhibited similar diagnostic performance. However, due to methodological differences between the two systems, careful interpretation of their results is needed in clinical applications.

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.