In-vivo diagnostic test allergens in Europe: A call to action and proposal for recovery plan-An EAACI position paper

Severely compromised supply of patch test allergens in Europe hampers adequate diagnosis of occupational and non-occupational contact allergy. A European Society of Contact Dermatitis (ESCD), European Academy of Allergy and Clinical Immunology (EAACI), European Academy of Dermatology and Venereology (EADV) task forces 'Contact Dermatitis' and 'Occupational Skin Disease' position paper

Patch testing is the only clinically applicable diagnostic method for Type IV allergy. The availability of Type IV patch test (PT) allergens in Europe, however, is currently scarce. This severely compromises adequate diagnostics of contact allergy, leading to serious consequences for the affected patients. Against this background, the European Society of Contact Dermatitis (ESCD) has created a task force (TF) (i) to explore the current availability of PT substances in different member states, (ii) to highlight some of the unique characteristics of Type IV vs. other allergens and (iii) to suggest ways forward to promote and ensure availability of high-quality patch testing substances for the diagnosis of Type IV allergies throughout Europe. The suggestions of the TF on how to improve the availability of PT allergens are supported by the ESCD, the European Academy of Allergy and Clinical Immunology, and the European Academy of Dermatology and Venereology and intend to provide potential means to resolve the present medical crisis.

Comparison of skin prick test and prick-to-prick test with fruits and vegetables in the diagnosis of food allergy

INTRODUCTION

Prick-to-prick (PTP) test with fresh food is accepted as a reliable tool for measuring sensitization to fruits and vegetables. Not all fruits and vegetables are available throughout the year. The objective of this study was to investigate whether skin prick test (SPT) performed with frozen juice of fruits and vegetables (FJFV) is a good alternative to PTP tests performed with fresh fruits and vegetables (FFV).

METHODS

Adult patients suspected of having a food allergy to fruits and/or vegetables were included. A questionnaire was used to score symptoms after consumption of apple, kiwi, peach, tomato, and carrot. SPTs with FJFV, and PTP tests with FFV were performed. Intra-class correlation coefficients (ICC) between the SPT and PTP test results were calculated. The sensitivity and specificity of both diagnostic tests towards food allergen specific symptoms (FASS) were calculated.

RESULTS

Thirty-six patients were included. FASS was positive in 75% for apple, 53% for kiwi, 44% for peach, 25% for tomato, and 22% for carrot. ICC between SPT and PTP test results were moderate for apple (0.72) and kiwi (0.71), strong for peach (0.75) and tomato (0.89), and very strong for carrot (0.94). Sensitivity was equal for the SPT and PTP tests for apple (0.93), peach (0.81), and carrot (1.00), and comparable for kiwi (0.50 resp. 0.70), and tomato (0.44 resp. 0.56). Specificity was equal for apple (0.33), peach (0.15), and carrot (0.41), and comparable for kiwi (0.29 resp. 0.21) and tomato (0.80 resp. 0.72).

CONCLUSIONS

Results of SPT with FJFV and PTP test with FFV are comparable. SPT with FJFV is a good alternative in the daily practice of the allergists.

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.

Inconsistent Skin Prick Tests for Allergy to Birch Homologous Trees May Result from Cross-Reacting Allergens or Technical Errors

INTRODUCTION

Skin prick tests (SPTs) are the gold standard for diagnosis of allergic rhinitis (AR). A decrease in the number of allergens included in standard SPT panels has recently been debated - particularly regarding the cross-reacting homologous pollen from birch, alder, and hazel trees - but has not yet been implemented in clinical guidelines.

METHODS

A subgroup of patients with AR (n = 69) who showed inconsistent SPT results among birch, alder, and hazel was investigated in detail. Beyond SPT, patient workup included assessment of clinical relevance and various serological parameters (total IgE, and specific IgE to birch, alder, and hazel and to Bet v 1, Bet v 2, and Bet v 4).

RESULTS

More than half the study group had negative SPT results for birch but positive results for alder and/or hazel, and 87% of the study group was polysensitized, showing at least one more positive SPT result for other plants. Whereas 30.4% of patients showed serological sensitization to birch pollen extract, only 18.8% displayed positive specific IgE to Bet v 1. Clinical assessment revealed that most patients with AR were polysensitized and had perennial symptoms or symptoms also occurring during times other than tree flowering times. If the SPT panel is limited to testing birch only, 52.2% of patients in this subgroup would have been overlooked.

CONCLUSION

Inconsistent SPT results in the birch homologous group may result from cross-reacting allergens or technical errors. If patients report convincing clinical symptoms despite negative results from a reduced SPT panel or inconsistent results for homologous allergens, SPT should be repeated, and molecular markers should be added to achieve a correct diagnosis.

Allergy screening with extract-based skin prick tests demonstrates higher sensitivity over in vitro molecular allergy testing

BACKGROUND

As extract-based skin testing as well as in vitro tests for major allergens have their own advantages, both procedures are usually performed in routine settings. In times of shortages in medical staff and supplies, we asked ourselves, how many patients would be underdiagnosed, if only one test could be used.

METHODS

In a retrospective analysis, we investigated a cohort of 2646 patients seen by a single physician in a large Austrian outpatient allergy clinic in 2018. Only patients with an allergen source-specific history and pairs of extract-based skin prick (SPT) and in vitro molecular allergy tests to major allergens were included.

RESULTS

For all tested allergen sources, sensitivity was higher for SPT than for sIgE-based molecular allergy testing. Concerning 1006 birch pollen-allergic patients, 791 (78.6%) had positive results with both tests, while 153 (15.2%) only with the SPT and 62 (6.2%) only with the sIgE to Bet v1. The other allergen sources showed similar results: For house dust mite 816/1120 (72.9%), grass pollen 1077/1416 (76.1%) and cat 433/622 (69.6%) remained test-positive with both procedures, whereas in 276 (24.6%), 224 (15.8%) and 173 (27.8%) times only the SPT and 28 (2.5%), 115 (8.1%) and 16 (2.6%) times only the sIgE to Der p1/2/23, Phl p1/5 and Fel d1 showed a positive result. Each comparison was statistically significant (each p < 0.0001, Chi-squared test).

CONCLUSIONS

Screening for allergy with major molecular allergens has lower sensitivity when compared with extract-based skin tests. A combination of both is required for an optimal sensitivity.

EAACI position paper on the clinical use of the bronchial allergen challenge: Unmet needs and research priorities

Allergic asthma (AA) is a common asthma phenotype, and its diagnosis requires both the demonstration of IgE-sensitization to aeroallergens and the causative role of this sensitization as a major driver of asthma symptoms. Therefore, a bronchial allergen challenge (BAC) would be occasionally required to identify AA patients among atopic asthmatics. Nevertheless, BAC is usually considered a research tool only, with existing protocols being tailored to mild asthmatics and research needs (eg long washout period for inhaled corticosteroids). Consequently, existing BAC protocols are not designed to be performed in moderate-to-severe asthmatics or in clinical practice. The correct diagnosis of AA might help select patients for immunomodulatory therapies. Allergen sublingual immunotherapy is now registered and recommended for controlled or partially controlled patients with house dust mite-driven AA and with FEV1 ≥ 70%. Allergen avoidance is costly and difficult to implement for the management of AA, so the proper selection of patients is also beneficial. In this position paper, the EAACI Task Force proposes a methodology for clinical BAC that would need to be validated in future studies. The clinical implementation of BAC could ultimately translate into a better phenotyping of asthmatics in real life, and into a more accurate selection of patients for long-term and costly management pathways.

Homemade Food Allergen Extracts for Use in Skin Prick Tests in the Diagnosis of IgE-Mediated Food Allergy: A Good Alternative in the Absence of Commercially Available Extracts?

Introduction: The skin prick test (SPT) is the first step in the diagnosis of an immunoglobulin E (IgE)-mediated food allergy. The availability of commercial food allergen extracts is very limited, resulting in a need for alternative extraction methods of food allergens. The objective of this study was to compare the SPT results of homemade food allergen extracts with commercially available extracts. Methods: Adult patients with a suspected food allergy were included. Food allergen-specific symptoms were scored using a questionnaire. SPTs were performed with homemade and commercially available extracts (ALK-Abelló, Kopenhagen, Denmark) from almond, apple, hazelnut, peach, peanut, and walnut. Serum-specific IgE was measured with ISAC or ImmunoCAP™. Intra-class correlation coefficients (ICC) between the SPT results of both extract methods were calculated. The proportion of agreement with food allergen-specific symptoms was analyzed. Results: Fifty-four patients (mean age 36; range 19–69 years; female/male: 42/12) were included. The intra-class correlation coefficient (ICC) between the SPT results of both extract methods were strong for hazelnut 0.79 (n = 44) and walnut 0.78 (n = 31), moderate for apple 0.74 (n = 21) and peanut 0.66 (n = 28), and weak for almond 0.36 (n = 27) and peach 0.17 (n = 23). The proportion of agreement between SPT results and food allergen-specific symptoms was comparable for homemade and commercially available extracts, except for peach; 0.77 versus 0.36, respectively. Conclusion: In the diagnostic procedures to identify an IgE-mediated food allergy, homemade extracts from hazelnut and walnut appear to be a good alternative in the absence of commercially available food allergen extracts.

Advances and highlights in allergic rhinitis

Allergic rhinitis (AR) is a growing public health, medical and economic problem worldwide. The current review describes the major discoveries related to AR during the past 2 years, including risk factors for the prevalence of AR, the corresponding diagnostic strategy, precise underlying immunological mechanisms, and efficient therapies for AR during the ongoing global "coronavirus disease 2019" (COVID-19) pandemic. The review further attempts to highlight future research perspectives. Increasing evidence suggests that environmental exposures, climate changes, and lifestyle are important risk factors for AR. Consequently, detailed investigation of the exposome and the connection between environmental exposures and health in the future should provide better risk profiles instead of single predictors, and also help mitigate adverse health outcomes in allergic diseases. Although patients with dual AR, a newly defined AR phenotype, display perennial and seasonal allergens-related nasal symptoms, they are only allergic to seasonal allergens, indicating the importance of measuring inflammation at the local sites. Herein, we suggest that a combination of precise diagnosis in local sites and traditional diagnostic methods may enhance the precision medicine-based approach for management of AR; however, this awaits further investigations. Apart from traditional treatments, social distancing, washing hands, and disinfection are also required to better manage AR patients in the ongoing global COVID-19 pandemic. Despite recent advances in understanding the immune mechanisms underlying the effects of allergen immunotherapy (AIT), further understanding changes of cell profiles after AIT and accurately evaluate the efficacy of AIT are required.

Molecular allergology approach to allergic asthma

Allergic asthma is a frequently encountered and well described asthma phenotype. However, its precise mechanisms are less known. The tools for targeted selection of patients for an optimal response to intervention (prevention or treatment) are also lacking. Here we explore the potential of the molecular allergology approach to achieve a better understanding of allergic asthma mechanisms, a precise diagnosis and an optimal management of these patients.

Differentiation of COVID-19 signs and symptoms from allergic rhinitis and common cold: An ARIA-EAACI-GA2 LEN consensus

Background

Although there are many asymptomatic patients, one of the problems of COVID‐19 is early recognition of the disease. COVID‐19 symptoms are polymorphic and may include upper respiratory symptoms. However, COVID‐19 symptoms may be mistaken with the common cold or allergic rhinitis. An ARIA‐EAACI study group attempted to differentiate upper respiratory symptoms between the three diseases.

Methods

A modified Delphi process was used. The ARIA members who were seeing COVID‐19 patients were asked to fill in a questionnaire on the upper airway symptoms of COVID‐19, common cold and allergic rhinitis.

Results

Among the 192 ARIA members who were invited to respond to the questionnaire, 89 responded and 87 questionnaires were analysed. The consensus was then reported. A two‐way ANOVA revealed significant differences in the symptom intensity between the three diseases (p < .001).

Conclusions

This modified Delphi approach enabled the differentiation of upper respiratory symptoms between COVID‐19, the common cold and allergic rhinitis. An electronic algorithm will be devised using the questionnaire.

Update on Type-1 Allergy Diagnostics

Diagnostics in type-1 allergy rely on medical history and clinical examination. Extent and severity of signs and symptoms can be documented by standardized scores and questionnaires. Both skin prick test and intradermal test are useful for search of immunoglobulin E-mediated sensitizations but the availability of commercially available diagnostic extracts has been markedly reduced during the last years. Investigation of total and of specific serum IgE is the most important in vitro diagnostic analyte in type-1 allergy. Identification of the individual molecules to which patients are sensitized, known as molecular or component-resolved diagnostics (CRD), has recently markedly improved management of type-1 allergy to pollen, food and hymenoptera venoms. Main features of CRD are increased analytic sensitivity, detection of cross-reactivity and determination of individual sensitization profiles which allow for risk assessment and facilitate decisions for or against allergen immunotherapy. Basophil activation test as well as determination of selected biomarkers (e.g. tryptase) may also be helpful in some cases. If any allergy test is positive, one will have to distinguish reactions, which are clinically relevant, from those, which are not. In vivo provocation tests (e.g. nasal provocation, oral drug or food challenge) may help to clarify the relevance of a sensitization.

[New allergens for occupational dermatology?]

BACKGROUND

The environment is continuously subject to change. Exposures in the work environment and therefore the importance of occupational type I and type IV allergens may change.

OBJECTIVES

The most important trends concerning occupational allergens, new occupational allergens/allergen exposures, the diagnostic procedure to detect new allergens in practice and regulatory developments are presented.

MATERIALS AND METHODS

Building on known relevant allergen exposures in occupational dermatology, published trends from clinical cohorts are evaluated and a systematic literature search (PubMed 2016-2021) for new occupational allergens is also performed RESULTS: Occupations with the highest incidence of occupational allergic contact urticaria and/or protein contact dermatitis include bakers, farmers and farm workers, veterinary technicians, veterinarians, cooks, dairy and livestock workers, gardeners, and hairdressers. The highest risk of developing occupational contact dermatitis is in health care, agriculture, metalworking occupations and machine operators, the food sector, service industries, and construction occupations. The search strategy "new occupational allerg*" yielded 603 hits and "novel occupational allerg*" 158 hits. A total of 25 papers included results relevant to the research question and were processed. New protein-based immediate-type allergens, as well as contact allergens (haptens) relevant for occupational dermatology, are presented.

CONCLUSIONS

Current trends on known occupational allergens and new occupational allergens in the period 2016-2021 can be identified. Only a thorough individual workplace history and testing of patients' own materials can identify new allergens in occupational dermatology.

Reaction frequency to the skin prick test of inhalant and food allergens in children

OBJECTIVE:

When applied by well-trained personnel, skin prick test (SPT) for a variety of inhalant and/or food allergens is a safe procedure although it may rarely cause systemic reaction. In this article, our aim was to evaluate the reactions after SPTs for the past 6 years in Turkish children having various allergic symptoms brought to our clinic.

METHODS:

The results of the SPTs, performed between May 2013 and March 2019, of 12.529 patients whose ages vary from 2 months to 18 years have been retrospectively evaluated.

RESULTS:

The average age of the patients who were included in this study was 6.12±4.38 years and 46.4% of them were female. When the patients were categorized according to the diagnosis, it was observed that 4.858 of them with symptoms suggesting asthma; 2.720 of them having symptoms suggesting allergic rhinitis; 1.795 of them having rashes; 906 of them with atopic dermatitis; 352 of them having symptoms suggesting food allergy and the remaining 1.898 with symptoms suggesting various diagnoses. In this study, which reflects our 6-year experience from the results of 12.529 patients, post-SPT reactions have been observed in 9 out of 12.529 patients (0.07%). They were three females and six males. These reactions were observed in 3 eczemas, 2 urticaria, 2 allergic rhinitis, and 2 suggested diagnosis of asthma patients. Their mean age was 5.9±3.5 years. SPT reactions were mostly seen in our five patients having skin disorder (eczema and rashes). The most frequent symptom of vasovagal reaction was syncope, occuring between 1 and 20 min after SPT, in eight of nine patients.

CONCLUSION:

During our study, any systemic reaction or anaphylaxis to SPT was not observed. The non-systemic reaction (vasovagal reaction) rate was 7/10.000, similar to the literature.

Microarray-Based Allergy Diagnosis: Quo Vadis?

More than 30% of the world population suffers from allergy. Allergic individuals are characterized by the production of immunoglobulin E (IgE) antibodies against innocuous environmental allergens. Upon allergen recognition IgE mediates allergen-specific immediate and late-phase allergic inflammation in different organs. The identification of the disease-causing allergens by demonstrating the presence of allergen-specific IgE is the key to precision medicine in allergy because it allows tailoring different forms of prevention and treatment according to the sensitization profiles of individual allergic patients. More than 30 years ago molecular cloning started to accelerate the identification of the disease-causing allergen molecules and enabled their production as recombinant molecules. Based on recombinant allergen molecules, molecular allergy diagnosis was introduced into clinical practice and allowed dissecting the molecular sensitization profiles of allergic patients. In 2002 it was demonstrated that microarray technology allows assembling large numbers of allergen molecules on chips for the rapid serological testing of IgE sensitizations with small volumes of serum. Since then microarrayed allergens have revolutionized research and diagnosis in allergy, but several unmet needs remain. Here we show that detection of IgE- and IgG-reactivity to a panel of respiratory allergens microarrayed onto silicon elements is more sensitive than glass-based chips. We discuss the advantages of silicon-based allergen microarrays and how this technology will allow addressing hitherto unmet needs in microarray-based allergy diagnosis. Importantly, it described how the assembly of silicon microarray elements may create different microarray formats for suiting different diagnostic applications such as quick testing of single patients, medium scale testing and fully automated large scale testing.

Allergic rhinitis

Allergic rhinitis (AR) is caused by immunoglobulin E (IgE)-mediated reactions to inhaled allergens and is one of the most common chronic conditions globally. AR often co-occurs with asthma and conjunctivitis and is a global health problem causing major burden and disability worldwide. Risk factors include inhalant and occupational allergens, as well as genetic factors. AR impairs quality of life, affects social life, school and work, and is associated with substantial economic costs. The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative classified AR into intermittent or persistent and mild or moderate/severe. The diagnosis is based on the clinical history and, if needed in patients with uncontrolled rhinitis despite medications or with long-lasting symptoms, on skin tests or the presence of serum-specific IgE antibodies to allergens. The most frequently used pharmacological treatments include oral, intranasal or ocular H₁-antihistamines, intranasal corticosteroids or a fixed combination of intranasal H₁-antihistamines and corticosteroids. Allergen immunotherapy prescribed by a specialist using high-quality extracts in stratified patients is effective in patients with persistent symptoms. Real-world data obtained by mobile technology offer new insights into AR phenotypes and management. The outlook for AR includes a better understanding of novel multimorbid phenotypes, health technology assessment and patient-centred shared decision-making.

New guidance on the regulation of allergen products: key aspects and outcomes

PURPOSE OF REVIEW

Key aspects and outcomes from the recently published guidance on the regulation of allergen products are summarized.

RECENT FINDINGS

A new regulatory guideline has been published to enhance harmonized national approaches on the regulation of allergen products and thereby strengthen the availability of high-quality products across the European Union (EU). As the guideline was developed, critical aspects for allergen products regulation were identified and are discussed in the document, including recommendations on the regulatory procedures to be applied for diagnostics, allergen immunotherapy products and named-patient products.

SUMMARY

The new guidance is expected to provide clarifications on and support harmonization of the regulation of allergen products in the EU.

Does the principle of homologous groups allow a reduction of allergens in the skin prick test panel?

PURPOSE

Regulatory and economic conditions drive the application of the concept of homologous groups on therapeutic and diagnostic formulations. In this context, a possible reduction of allergens in the skin prick test panel in the clinical routine should be investigated for the grass, birch and Dermatophagoides homologous group.

METHODS

Grass and cultivated rye skin prick test results of 1101 patients, birch/hazel/alder skin prick test results of 1131 patients and 1068 Dermatophagoides pteronyssinus and farinae skin prick tests were retrospectively evaluated with regard to sensitivity and false-negative rate detecting sensitization against cultivated rye with grass skin prick test, sensitization against hazel and/or alder with birch skin prick test and sensitization towards Dermatophagoides farinae with Dermatophagoides pteronyssinus skin prick test.

RESULTS

Skin prick test results in all groups highly correlated in Spearman Rank Order correlation. Sensitivity of grass skin prick test detecting sensitization against cultivated rye was highest with 98.9%, sensitivity of birch skin prick test detecting sensitization toward hazel and alder was 95.6 and 90.0%, respectively. Sensitivity of skin prick test with Dermatophagoides pteronyssinus detecting sensitization towards Dermatophagoides farinae was 93.6%. Only 26 patients with positive rye, hazel, alder or Dermatophagoides farinae skin prick test that were overlooked by grass, birch or Dermatophagoides pteronyssinus skin prick test reported allergic symptoms.

CONCLUSION

In routine clinical practice, sensitization against cultivated rye can safely be detected by skin prick test with grass allergen. In addition, the sensitivity of birch skin prick test is high in terms of sensitization towards hazel, but lower for alder. Sensitivity of Dermatophagoides pteronyssinus skin prick test also is high to detect sensitization towards Dermatophagoides farinae. Further research will indicate if several skin prick test allergens will disappear and be completely replaced by a single skin prick test based on the principle of homologous groups.