The crux with a reliable in vitro and in vivo diagnosis of allergy

Assessing the contributions of phylogenetic and environmental determinants of allergic cosensitization to fungi in humans

BACKGROUND

Understanding how allergies to 1 environmental fungus can lead to cosensitization to related fungi is important for the clinical management of allergies. Cosensitization can be caused by monosensitization combined with antibody cross-reactivity, or by coexposures driving independent sensitizations. A pioneering study showed that patterns of IgE cosensitization among 17 fungal species mirror fungal phylogeny. This could reflect either epitope or habitat similarity. Thanks to an improved understanding of fungal phylogeny, larger serologic testing datasets, and environmental data on household fungi, we can now characterize the relationship between cosensitization, species similarity, and likely coexposure with greater precision.

OBJECTIVE

To assess the degree to which IgE cosensitization in a group of 17 fungi can be attributed to species similarity or environmental coexposure.

METHODS

Cosensitization patterns among 17 fungal species were estimated from a dataset of approximately 8 million serologic tests on 1.6 million patients. Linear regression of cosensitization on phylogenetic distance and imputed coexposure was performed. In addition, branch lengths for the phylogenetic tree were re-estimated on the basis of cosensitization and compared with corresponding phylogenetic branch lengths.

RESULTS

Phylogenetic distance explains much of the observed cosensitization (adjusted r2 = .68, p < .001). Imputed environmental coexposures and test co-ordering patterns do not significantly predict cosensitization. Branch length comparisons between the cosensitization and phylogenetic trees identified several species as less cosensitizing than phylogenetic distance predicts.

CONCLUSION

Combined evidence from clinical IgE testing data on fungi, along with phylogenetic and environmental exposure data, supports the hypothesis that cosensitization is caused primarily by monosensitization plus cross-reactivity, rather than multisensitization. A serologic test result should be interpreted as pointing to a group of related species that include the sensitizing agent rather than as uniquely identifying the agent. The identified patterns of cross-reactivity may help optimize test panel design.

Predictive Value of Adenoid-Nasopharyngeal Ratio in the Diagnosis of Secretory Otitis Media

OBJECTIVES

To explore the associated factors of otitis media with effusion (OME) and analyze the diagnostic value of the adenoid-nasopharyngeal (A/N) ratio to OME.

METHODS

Patients with adenoid hypertrophy (AH) recently in 2 years were collected, including sex, age, duration, with/without rhinosinusitis, and examination results, including Cone Beam Computerized Tomography (CBCT) sinus imaging, tympanometry, pure tone audiometry (PTA), blood test, and allergen detection. According to Liden/Jerger's classification, the patients were divided into two groups: Type B and type C, which were defined as the tympanometry abnormal group (TAG), and the rest were classified as the tympanometry normal group (TNG).

RESULTS

A total of 316 children were included in this study. Age and duration were significantly younger and shorter in TAG (6.0(4.0-9.0) vs.5.0(4.0-7.0)); 12.0(4.0-24.0) vs.6.0(2.0-12.0)). Compared to TNG, the allergen test results of fx5 (protein, milk, cod, wheat, peanut, and soybean) in TAG were higher (0.09(0.04-0.25) vs.0.14(0.05-0.45)), but eosinophilia in blood was lower (count: 0.21(0.13-0.35) vs. 0.18(0.12-0.27); ratio: 3.10 (1.90-4.70) vs. 2.50 (1.65-3.80)). A/N ratio and Visual obstruction ratio had a statistical difference (Z = -3.770, P < .01) but the two ratios didn't have too much disparity (0.82(0.74-0.88) VS 0.80(0.75-0.80)), and they had a positive correlation (r = 0.345, P < .01). A/N ratio of TAG was higher than TNG (0.78(0.70-0.85) vs. 0.86(0.82-0.90)) and had a positive correlation with increasing negative middle ear pressure (r = -3.777, P < .01). A/N ratio was an associated factor of OME (OR:1355.611, P = .006), the cut-off value of A/N ratio was 0.815(sensitivity: 75.3%, specificity: 64.3%, area under the curve (AUC): 0.747).

CONCLUSIONS

A/N ratio indirectly reflected the abnormality of tympanometry in this study. When A/N ratio reaches 0.815, patients are at a higher risk of having OME so it could be a predictor of OME in patients with adenoid hypertrophy.

Epigenetic/genetic variations in CG-rich elements of immune-related genes contribute to food allergy development during childhood

BACKGROUND

Genetic areas of FOXP3 TSDR, human leukocyte antigen-G (HLA-G) upstream of CpG island 96, CpG41 and CpG73 islands of the HLA-DRB1 and HLA-DQB1 genes respectively, previously documented to display immune-modulatory properties, were subjected to epigenetic/genetic analysis to assess their influence in IgE-mediated food allergy (FA) development in children.

METHODS

Sixty-four orally challenged and IgE-tested food allergic subjects together with 44 controls were recruited. Targeted pyrosequencing analysis to detect DNA methylation status and genetic variations was utilized and experimental results obtained were analyzed by a statistical software platform and correlated to clinical data. Also, transcription factor (TF) binding sites in study areas were unmasked by the JASPAR prediction database.

RESULTS

Parents' smoking was significantly correlated with aberrant methylation patterns, regardless of food allergic or control status. HLA-G promoter region showed a trend for hypomethylation in food allergic subjects, with one of the CG sites displaying significantly decreased methylation values. Rs1233333, residing within the HLA-G promoter region preserved a protective role toward DNA methylation. Variable methylation patterns were recorded for CpG41 of the HLA-DRB1 gene and hypermethylation of the region was significantly correlated with the presence of single nucleotide polymorphisms (SNPs). TFs' recognition sites, located in studied genetic areas and exerting pivotal regulatory biological roles, are potentially affected by divergent DNA methylation status.

CONCLUSIONS

We propose that HLA-G expression is triggered by food-derived allergens, providing a Treg^{FoxP3-/HLA-G+} subpopulation generation to promote direct immune tolerance. Furthermore, clear evidence is provided for the underlying co-operation of genetic polymorphisms with epigenetic events, mainly at the CpG41 island of the HLA-DRB1 gene, which needs an extended investigation and elucidation.

Three patterns of sensitization to mugwort, timothy, birch and their major allergen components revealed by Latent class analysis

BACKGROUND

Mugwort, timothy, and birch are commonly spread pollen allergens across China. Although several studies have described the rates of sensitization to mugwort, timothy, and birch in China, most of them just on specific whole-allergen extracts but little was known about the co-sensitization characteristics of its allergen components. This study aimed to explore the patterns of sensitization to mugwort, timothy, birch, and their major allergen components.

METHOD

Serum specific IgE (sIgE) levels of allergen components of mugwort, timothy, birch, and cross-reactive carbohydrate determinants (CCD) were detected in 160 patients whose serum showed positive results to at least one of mugwort, timothy, and birch allergens via EUROBlotMaster system. Skin prick testing was utilized to assess the allergic reaction of grass, weed, and tree allergens. Latent class analysis was used to identify underlying patterns of sensitization to a series of allergen components and their corresponding extracts.

RESULTS

88.8% of patients with allergic rhinitis and/or asthma were positive for mugwort-sIgE, 30% for timothy-sIgE, and 32.5% for birch-sIgE. By using the LCA model, three sensitization patterns as "Mugwort, Art v 4, Bet v 2 and Phl p 12 co-sensitized", "Timothy, mugwort, and CCD co-sensitized", "Mugwort and Art v 1 co-sensitized" were revealed based on optimal statistical fit in this study. Compared with other clusters, participants in "Mugwort, Art v 4, Bet v 2 and Phl p 12 co-sensitized" pattern were associated with higher sensitization rates of common grass and tree pollens allergen. The spearman's coefficient between CCD and timothy was larger than the corresponding values of CCD with mugwort or birch.

CONCLUSION

CCD and profilin, as minor allergens in pollens, were associated with other pollen sIgE false positives presumably due to cross-reactivity. Patients sensitized with profilin had a significantly higher risk of sensitization to other pollens.

Evaluation of a fully automated and completely quantitative allergen-specific IgE and total IgE detection assay

Based on the current urgent need for an in vitro quantitative detection system for allergens in most hospitals in China, we introduced a novel allergen-specific immunoglobulin E detection system that employs a solid phase enzyme-linked immunoassay and evaluated its clinical performance. The system uses a special reaction component (innovative patents) to reduce the reaction time to 12 min, achieving point-of-care testing for allergy management, which is impressive compared to the 3-18 h testing time for all other systems. In addition, the AILEX system has excellent consistency with the ImmunoCAP reference method system; therefore, we recommend the introduction of the AILEX system for clinical auxiliary diagnosis in medical units.

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.

Sensitization to Fungi in Atopic Dermatitis Patients 14 Year and Older - Association with Other Atopic Diseases and Parameters

Background:

Fungi as a source of allergen are still largely neglected in basic research as well as in clinical practice. This study aimed to highlight the impact of fungal allergens in a group of patients suffering from atopic dermatitis (AD).

Aims and Objectives:

The evaluation of the sensitization to fungi in AD patients aged 14 year and older and the evaluation of the relation of fungal sensitization to the occurrence of other atopic diseases and parameters.

Materials and Methods:

All patients satisfying inclusion criteria attending our hospital between 2008 and 2017 were included in the study. The complete dermatological and allergological examinations were performed in all included patients including examination of specific immunoglobulin E, skin prick test to mixture of fungi and inhalant allergens, evaluation of asthma bronchiale, rhinitis, onset of AD, family history about atopy, duration of eczematous lesions, severity of AD. Pairs of these categories were entered in the contingency tables and the Chi-square test for relationship of these variables was performed with the level of significance set below 5%.

Results:

Three hundred and thirty-one patients were included in the study; the average age was 26.8 years. The sensitization to fungi was recorded in 100 patients (30%). In these patients, the occurrence of asthma bronchiale, rhinitis, family history about atopy, sensitization to grass and trees was significantly higher than in patients without sensitization to fungi. We did not find any significant relation between the sensitization to fungi and the severity of AD, no relation was also found between the sensitization to fungi and sensitization to mites, animal dander, bird feather, and dust.

Conclusion:

The occurrence of asthma bronchiale, rhinitis, family history about atopy, sensitization to grass and trees was significantly higher in AD patients with sensitization to fungi. No relation was found between the severity of AD and the sensitization to fungi.

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.

An immunodiagnostic assay for quantitation of specific IgE to the major pollen allergen component, Pas n 1, of the subtropical Bahia grass

BACKGROUND

Pollens of the Panicoideae subfamily of grasses including Bahia (Paspalum notatum) are important allergen sources in subtropical regions of the world. An assay for specific IgE to the major molecular allergenic component, Pas n 1, of Bahia grass pollen (BaGP) would have immunodiagnostic utility for patients with pollen allergy in these regions.

METHODS

Biotinylated Pas n 1 purified from BaGP was coated onto streptavidin ImmunoCAPs. Subjects were assessed by clinical history of allergic rhinitis and skin prick test (SPT) to aeroallergens. Serum total, BaGP-specific and Pas n 1-specific IgE were measured.

RESULTS

Pas n 1 IgE concentrations were highly correlated with BaGP SPT (r = 0.795, p < 0.0001) and BaGP IgE (r = 0.915, p < 0.0001). At 0.23 kU/l Pas n 1 IgE, the diagnostic sensitivity (92.4%) and specificity (93.1%) for the detection of BaGP allergy was high (area under receiver operator curve 0.960, p < 0.0001). The median concentrations of Pas n 1 IgE in non-atopic subjects (0.01 kU/l, n = 67) and those with other allergies (0.02 kU/l, n = 59) showed no inter-group difference, whilst grass pollen-allergic patients with allergic rhinitis showed elevated Pas n 1 IgE (6.71 kU/l, n = 182, p < 0.0001). The inter-assay coefficient of variation for the BaGP-allergic serum pool was 6.92%.

CONCLUSIONS

Pas n 1 IgE appears to account for most of the BaGP-specific IgE. This molecular component immunoassay for Pas n 1 IgE has potential utility to improve the sensitivity and accuracy of diagnosis of BaGP allergy for patients in subtropical regions.

The contribution of biotechnology toward progress in diagnosis, management, and treatment of allergic diseases

'Biotechnology' has been intuitively used by humans since thousands of years for the production of foods, beverages, and drugs based on the experience without any scientific background. However, the golden era of this discipline emerged only during the second half of the last century. Incredible progresses have been achieved on all fields starting from the industrialization of the production of foods to the discovery of antibiotics, the decipherment of the genetic code, and rational approaches to understand and define the status we now call 'healthy'. The extremely complex interactions between genetic background, life style, and environmental factors influencing our continuously increasing life span have become more and more evident and steadily generate new questions which are only partly answered. Here, we try to summarize the contribution of biotechnology to our understanding, control, and cure of IgE-mediated allergic diseases. We are aware that a review of such a vast topic can never cover all aspects of the progress achieved in the different fields.

IgE antibodies in occupational asthma: are they causative or an associated phenomenon?

PURPOSE OF REVIEW

To evaluate recent data on the causative role of specific IgE antibodies, as well as the performance of IgE diagnostic tests, in allergic occupational asthma induced by high (HMW) or low-molecular-weight (LMW) agents.

RECENT FINDINGS

Skin prick testing (SPT) and specific IgE assays are useful to document allergy to most HMW allergens and some LMW agents. These tests, however, are limited by the lack of standardized and commercially available reagents. There is a wide variability among the quality of occupational allergen extracts used for SPT and the sensitivity of several SPT solutions is low. In addition, many individuals with allergen-specific serum IgE and/or positive SPT to specific HMW allergens do not have clinical symptoms. Sensitization or allergenic cross-reactivity to allergens or epitopes from unrelated sources may interfere in the diagnosis of IgE-mediated allergy, giving rise to false-positive results, particularly when cross-reactive carbohydrate determinants (CCDs) are involved. The immune responses to these ubiquitous structures may interfere with the diagnosis of occupational allergy. Component-resolved diagnosis of IgE-mediated allergic diseases (occupational and nonoccupational) using panels of native or recombinant allergens, or micro-arrayed allergens, have been proposed to identify specific molecules responsible for these disorders and to overcome false-positive in-vitro test results.

SUMMARY

Improvement and standardization of SPT solutions for occupational allergens are highly recommended. More refined diagnostic tools than specific IgE measurements are being developed, such as inhibition assays of IgE binding to CCDs with specific carbohydrate molecules, and component-resolved diagnosis.

Fungi: the neglected allergenic sources

Allergic diseases are considered the epidemics of the twentieth century estimated to affect more than 30% of the population in industrialized countries with a still increasing incidence. During the past two decades, the application of molecular biology allowed cloning, production and characterization of hundreds of recombinant allergens. In turn, knowledge about molecular, chemical and biologically relevant allergens contributed to increase our understanding of the mechanisms underlying IgE-mediated type I hypersensitivity reactions. It has been largely demonstrated that fungi are potent sources of allergenic molecules covering a vast variety of molecular structures including enzymes, toxins, cell wall components and phylogenetically highly conserved cross-reactive proteins. Despite the large knowledge accumulated and the compelling evidence for an involvement of fungal allergens in the pathophysiology of allergic diseases, fungi as a prominent source of allergens are still largely neglected in basic research as well as in clinical practice. This review aims to highlight the impact of fungal allergens with focus on asthma and atopic dermatitis.