Characterization of occupational sensitization by multiallergen immunoblotting in workers exposed to laboratory animals

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Allergen component analysis as a tool in the diagnosis and management of occupational allergy

We are now in the epoch of "molecular allergology" and numerous clinically relevant allergenic molecules are available improving the performance of in vitro allergen tests and allergen detection methods. This review is focusing on characterized occupational allergens and their implementation into the in vitro diagnosis for occupational allergy and in allergen detection methods. More than 400 occupational agents are identified and documented as being 'respiratory sensitizers', but currently only a limited number of them are characterized on the molecular level and available for routine diagnosis as native or recombinant allergens. One exception, however, is natural rubber latex (NRL) from Hevea brasiliensis still remaining an important occupational allergen source. Characterization of 15 NRL allergens led to the development of assays for the determination of allergen content of NRL materials and the implementation of component-resolved diagnosis (CRD) for specific IgE antibody measurement. Microarray or singleplex using recombinant or native allergens are reliable tools for NRL allergy diagnosis. In addition, NRL allergy is an excellent model for improving extract-based specific IgE measurement by amplification of NRL extract preparation with stable recombinant major allergen rHev b 5. Despite the many efforts to characterize the occupationally relevant wheat allergens for baker's asthma, the most frequently occurring forms of occupational asthma, the results are highly diverse. Wheat sensitization profiles of bakers showed great interindividual variability and no wheat allergen could be classified as the major allergen. For diagnosis of baker's asthma, a whole wheat extract is still the best option for specific IgE determination. But single wheat allergens might help to discriminate between wheat-induced food allergy, grass pollen allergy and baker's asthma. For workplace-related allergens like coffee, wood, soybean, seafood and moulds allergens are characterized and few of them are available, but their relevance for occupational sensitization routes should be verified in the further studies.

Fatores de riscos ocupacionais e implicações à saúde do trabalhador em biotérios

RESUMO Estudo transversal que avaliou as implicações à saúde dos trabalhadores de biotérios, bem como fatores de risco inerentes, em uma Instituição Federal de Ciências e Tecnologia. Os dados foram coletados por meio de um questionário semiestruturado e observação participante, em 2014. Foi evidenciado que os trabalhadores dos biotérios pesquisados em geral têm suas funções relacionadas com os fatores de risco físico, de acidente, ergonômico, biológico e organizacional/psicossocial. A pesquisa refletiu o quadro atual de deterioração das relações trabalho-saúde, sinalizando a necessidade de atualização constante no monitoramento na atenção à saúde desses trabalhadores.

Allergen component analysis as a tool in the diagnosis of occupational allergy

PURPOSE OF REVIEW

Rapid developments have been seen in molecular allergy diagnosis, based on the detection and quantification of specific IgE to single allergens. This review summarizes and discusses studies on allergen component analysis as a tool in the diagnosis of occupational allergy.

RECENT FINDINGS

More than 400 agents are identified as sensitizers of occupational asthma, but only very few are characterized on the molecular level and available for routine diagnosis. Baker's asthma is one of the most frequently occurring forms of occupational asthma caused by workplace-related inhalation of cereal flour mainly wheat. Wheat sensitization profiles of bakers show great interindividual variability and no wheat allergen could be classified as the major allergen. Component-resolved diagnosis is a useful tool for diagnosing natural rubber latex (NRL) allergy. In cases with unexpected high-latex IgE but without clinical symptoms application of crossreactive carbohydrate determinants are helpful to clarify the cause of IgE binding.

SUMMARY

Latex is an excellent model for component-resolved diagnosis and demonstrates well how to improve the diagnosis by using single allergens. For diagnosis of baker's asthma, a whole wheat extract is still the best option for specific IgE determination, but single wheat allergens might help to discriminate between wheat-induced food allergy, grass-pollen allergy, and baker's asthma. New diagnostic tools and platforms are promising, but further knowledge of molecules relevant for occupational asthma (as in wood dust allergens, enzymes, laboratory animal allergens, etc.) and for occupational hypersensitivity pneumonitis is necessary to improve and standardize the diagnostic tools.

New developments in work-related asthma

INTRODUCTION

Work-related asthma includes two subtypes: occupational asthma or asthma caused by specific agents (sensitizers or irritants) in the workplace, and work-exacerbated asthma or pre-existing asthma worsened by workplace exposures. Areas covered: This review provides an update on the definitions and the clinical features of the different work-related asthma subtypes as well as new insights into their etiology and the pathophysiological mechanisms involved. The diagnosis of work-related asthma should be made on objective basis using a constellation of clinical, physiologic and allergologic tests. Specific inhalation challenge with the suspected occupational agent(s) remains as the reference standard for diagnosis. A literature search was performed using the following terms: work-related asthma, occupational asthma, work-exacerbated asthma, irritant-induced asthma and etiological agents. Expert commentary: Studies focusing on the biological effects and mechanisms of environmental exposures in the development of sensitizer-induced or irritant-induced asthma in various workplace settings are of greatest interest. An integrative approach that combines clinical parameters with component-resolved diagnosis as well as inflammatory biomarkers appears to be very promising. Occupational allergy provides a good opportunity to understand the complex relationships between exposure to allergens in the workplace, interaction with genes and the co-exposures to other factors in the working environment.

Specific immunotherapy and biological treatments for occupational allergy

PURPOSE OF REVIEW

Occupational allergy represents a substantial health, social, and financial burden for the society. Its management is a complex task that, in selected cases, may also include allergen-specific immunotherapy. The purpose of this article is to review clinical data on allergen immunotherapy and biological treatments applied to occupational allergy in 2013.

RECENT FINDINGS

Immunotherapy in occupational allergic diseases has been scarcely used, and only for a few sensitizers, such as latex, flour, and Hymenoptera venom, partly due to the lack of standardized extracts. The recent use of the molecular diagnosis can improve the indication and selection of suitable allergens for preparing new standardized and powerful extracts for immunotherapy. Some recent reports suggest a beneficial role of treatment with omalizumab in workers with occupational asthma who continue to be exposed to the causal agent.

SUMMARY

Although scarce, available data suggest that immunotherapy and biological treatments may allow allergic workers to continue their work activity, but further studies are needed to standardize extracts and to evaluate the cost-effectiveness of these treatments, when exposure at the workplace cannot be avoided.

Identification and practical management of latex allergy in occupational settings

Allergy to natural rubber latex (NRL) from Hevea brasiliensis is a relevant occupational health hazard. The use of gloves and products manufactured with latex and environmental allergen exposure in the work environment are risks factors for the development of occupational allergy among different job categories. Healthcare workers have been the most commonly affected, but other professions with exposure to latex products such as hairdressers, cleaners, food handlers and those making natural rubber latex (NRL) products are also at risk of developing occupational allergy. Clinical manifestations of IgE-mediated latex allergy can range from troublesome skin disorders to life-threatening systemic reactions. It is very important to identify the occupational allergic diseases in their early stages in order to implement avoidance strategies. For this purpose, the interventions for prevention should emphasize the importance of latex allergy awareness and surveillance among exposed workforces.

Biological and genetic markers in occupational asthma

Occupational asthma (OA) is a complex disease that is often hard to diagnose due to difficulties in detecting relevant exposure, along with inherent differences in disease susceptibility. Numerous studies have attempted to identify relevant biological and genetic markers for OA and to devise tools capable of detecting exposure to the causative agent. Immunological markers, including skin prick test reactivity and specific IgE and IgG antibodies can be used to detect high-molecular-weight allergens in cases of baker's asthma. For OA induced by low-molecular-weight agents, such as isocyanate, potential biomarkers include serum-specific IgE and IgG antibodies to isocyanate-HSA conjugate and IgG to cytokeratin 19 and transglutaminase-2. For protein-based markers, ferritin/transferrin and vitamin D-binding protein levels have been suggested for isocyanate-OA. Genetic markers of susceptibility to isocyanate-OA include human leukocyte antigen and CTNNA3. Further investigations will be needed to identify better biomarkers for OA, which may be used to inform clinical decision.

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.

Animal allergen sensitization in veterinarians and laboratory animal workers

BACKGROUND

Animals secrete allergens into the environment and exposure to these in the workplace may cause sensitization.

AIMS

To identify the frequency of animal allergen sensitization and symptoms in animal workers.

METHODS

Using skin prick tests (SPT), we assessed sensitization to 15 mammal and bird allergens in animal workers and controls. We also recorded symptoms and pulmonary function tests.

RESULTS

There were 100 animal workers and 50 controls included in the study. Thirty-six per cent of animal workers and 10% of controls had positive SPT (P < 0.001, odds ratio [OR] = 5.1, 95% CI 1.7-16.0). The most common sensitizations were to horse (16% in animal workers versus 0% in controls, P < 0.01), canary (16% in animal workers versus 2% in controls, P < 0.05, OR = 9.3, 95% CI 1.2-194), cattle (13% in animal workers versus 0% in controls, P < 0.05), cat (12% in animal workers versus 6% in controls, not significant), rabbit and hamster (10% each in animal workers versus 0% in controls, P < 0.05). Allergy symptoms were reported by 52 animal workers, but only 36 of them had positive SPT. Twelve animal workers had abnormal pulmonary function tests and six had positive SPT.

CONCLUSIONS

Animal workers are at high risk of occupational sensitization to animal allergens. Exposure should be minimized through control measures and worker education about the risks of exposure and sensitization.

Identification and isolation of a Fel d 1-like molecule as a major rabbit allergen

BACKGROUND

Rabbits are increasingly kept as domestic pets. Several rabbit allergens have been characterized. However, their sequences are still elusive, and none of these molecules are available for diagnosis.

OBJECTIVE

We sought to isolate major allergens from the rabbit Oryctolagus cuniculus and to investigate their importance in sensitized patients.

METHODS

Proteins were extracted from rabbit hair, and IgE-reactive proteins were purified by using sequential chromatography. Allergens were characterized by means of N-terminal sequencing and mass spectrometry. IgE reactivity to a new allergen was analyzed in sera of 35 patients sensitized to rabbits in a domestic setting. A model of the crystal structure of the isolated proteins was constructed.

RESULTS

A new IgE-reactive allergen, Ory c 3, was identified as rabbit lipophilin. The molecule that belongs to the secretoglobin family is a heterodimer of 18 to 19 kDa composed of 2 polypeptide chains, CL2 and AL. CL2 has a predicted N-linked glycosylation site confirmed by using mass spectrometry. Of the 35 patients with rabbit allergy studied, 27 (77%) had IgE to both the glycosylated and deglycosylated Ory c 3 heterodimer. Allergenicity of Ory c 3 was confirmed by using skin prick tests and the basophil activation assay. Modeling of the structure revealed a marked homology to Fel d 1, the major cat allergen. However, no IgE cross-reactivity was detected between Fel d 1 and Ory c 3.

CONCLUSION

The rabbit lipophilin heterodimer AL-CL2 has been identified as a major rabbit allergen. After Fel d 1, Ory c 3 is the second mammalian secretoglobin shown to be a major allergen.