Occupational Latex Allergy: the Current State of Affairs

Comparison of high- and low-molecular-weight sensitizing agents causing occupational asthma: an evidence-based insight

INTRODUCTION

The many substances used at the workplace that can cause sensitizer-induced occupational asthma are conventionally categorized into high-molecular-weight (HMW) agents and low-molecular-weight (LMW) agents, implying implicitly that these two categories of agents are associated with distinct phenotypic profiles and pathophysiological mechanisms.

AREAS COVERED

The authors conducted an evidence-based review of available data in order to identify the similarities and differences between HMW and LMW sensitizing agents.

EXPERT OPINION

Compared with LMW agents, HMW agents are associated with a few distinct clinical features (i.e. concomitant work-related rhinitis, incidence of immediate asthmatic reactions and increase in fractional exhaled nitric oxide upon exposure) and risk factors (i.e. atopy and smoking). However, some LMW agents may exhibit 'HMW-like' phenotypic characteristics, indicating that LMW agents are a heterogeneous group of agents and that pooling them into a single group may be misleading. Regardless of the presence of detectable specific IgE antibodies, both HMW and LMW agents are associated with a mixed Th1/Th2 immune response and a predominantly eosinophilic pattern of airway inflammation. Large-scale multicenter studies are needed that use objective diagnostic criteria and assessment of airway inflammatory biomarkers to identify the pathobiological pathways involved in OA caused by the various non-protein agents.

Assessing the impact of the COVID-19 pandemic on latex glove usage and latex allergy complaints among nurses: A descriptive study

BACKGROUND

The coronavirus 2019 (COVID-19) pandemic has led to a significant increase in the use of latex gloves among nurses. However, concerns about the rise in latex allergies and related complaints due to this increase remain uncertain.

OBJECTİVE

This study aims to assess the rates of latex glove usage and allergy-related complaints among nurses working in hospitals during the COVID-19 pandemic.

METHODS

Between May 15 and June 15, 2021, ethical approvals were obtained for a cross-sectional study involving 448 volunteer nurses. Descriptive statistics were used to represent categorical values as counts (n) and percentages (%), while continuous values were represented as mean±standard deviation. The normal distribution of the data was assessed using the Kolmogorov-Smirnov and Shapiro-Wilk tests. Comparative analyses were conducted using paired sample t-test, Pearson's chi-squared (x2) test, McNemar's chi-squared (x2) test, and Spearman correlation analysis.

RESULTS

Before the pandemic, the average number of invasive procedures was 45.13±26.48, whereas during the pandemic, this rate increased to 50.23±29.14. The average glove usage duration went from 7.69±3.13 hours to 14.73±3.68 hours during the pandemic. Among nurses, the rate of allergic symptoms, which was previously at 31.5%, rose to 33.3% during the pandemic.

CONCLUSİON

This study revealed a significant increase in daily invasive procedures and the use of latex gloves among nurses during the pandemic period. Simultaneously, the frequency of allergic symptoms also rose. These findings underscore the importance of awareness and preventive measures, particularly regarding latex allergies, in the healthcare field.

Latex Allergy - From Discovery to Component-resolved Diagnosis

Latex allergy is a hypersensitivity response to natural rubber latex (NRL) proteins or rubber chemicals used in the manufacture of latex products. An accurate diagnosis is the first step in the effective management of individuals with latex allergy, especially in high-risk groups, such as healthcare workers and those affected by spina bifida. Diagnosis is based on the clinical history and an accurate allergological evaluation. In the case of type I IgE-mediated hypersensitivity reactions, which can manifest urticaria, angioedema, rhinoconjunctivitis, asthma and anaphylaxis after latex exposure, skin prick tests or latex-specific IgE (sIgE) antibody detection using serological assays can be performed to confirm sensitization. Instead, in the case of contact dermatitis, a patch test can be applied to confirm the presence of a type IV T cell-mediated hypersensitivity reaction to rubber accelerators or additives. Basophils activation tests or challenge tests may be performed if there's an incongruity between the clinical history and the results of in vivo and in vitro tests. The aim of this review is to analyze the current state of the art of diagnostic techniques for latex allergy and algorithms employed in clinical practice and possible future developments in this field.

Latex Allergy in Children

Notwithstanding the efforts made in the last decades to mitigate the consequences of natural rubber latex allergy, this disease continues to be a major health problem, especially in developing countries. The categories of patients with greater and frequent exposure to latex (such as health care professionals and, in the pediatric field, subjects who undergo repeated surgery, e.g., those suffering from spina bifida and urogenital malformations) have an increased risk of developing sensitization and allergy to latex. Herein we provide an overview of the current knowledge and practical recommendations with a focus on epidemiology, diagnostics, and management (including both prevention and therapy) in order to guide a correct recognition and containment of this potentially fatal condition.

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.

Update on latex allergy: New insights into an old problem

Despite the efforts made to mitigate the consequences of this disease, natural rubber latex allergy (NRLA) continues to be a global health problem and is still considered one of the main worries in the working environment in many countries throughout the world. Due to thousands of products containing latex, it is not surprising that the current statistics suggest that prevalence remains high among healthcare workers and susceptible patients. In developed countries, reduction in the prevalence of IgE-mediated allergy to latex proteins from gloves may lead to lax attention by health care personnel. On the other hand, this situation is different in developing countries where there is a lack of epidemiological data associated with a deficit in education and awareness of this issue. The aim of this review is to provide an update of the current knowledge and practical recommendations regarding NRLA by allergologists from different parts of the world with experience in this field.

Current state of occupational latex allergy

PURPOSE OF REVIEW

During the 1980s, natural rubber latex (NRL) emerged as a major cause of occupational allergy and asthma, especially in healthcare workers using powdered NRL gloves. Increased recognition of NRL allergies and transfer of research findings into prevention strategies resulted into an almost elimination of this health problem. Here, the current knowledge on allergens, their use in diagnostics, prevalence data of occupational NRL allergy and the status of prevention strategy are summarized.

RECENT FINDINGS

While the current studies conducted in high-income countries show that prevention measures have reduced NRL allergy, this does not yet apply worldwide. For latex allergy diagnosis, it is important that recombinant allergens as reliable tools are available, because in several European countries and the United States, NRL skin prick test extracts and powdered latex gloves for bronchial challenge test are no longer commercially available, leading to a deficit in diagnostic tools. Due to the fact that latex is suitable with good properties as a raw material for gloves, alternatives with significantly lower protein content and without cross-reactive structures to latex proteins are sought.

SUMMARY

Awareness of the sensitization risk associated with the use of latex gloves should still be present in all occupational settings.

Occupational Respiratory Allergy: Risk Factors, Diagnosis, and Management

Occupational allergies are among the most common recorded occupational diseases. The skin and the upper and lower respiratory tract are the classical manifestation organs. More than 400 occupational agents are currently documented as being potential "respiratory sensitizers" and new reported causative agents are reported each year. These agents may induce occupational rhinitis (OR) or occupational asthma (OA) and can be divided into high-molecular weight (HMW) and low-molecular weight (LMW) agents. The most common occupational HMW agents are (glycol)proteins found in flour and grains, enzymes, laboratory animals, fish and seafood, molds, and Hevea brasiliensis latex. Typical LMW substances are isocyanates, metals, quaternary ammonium persulfate, acid anhydrides, and cleaning products/disinfectants. Diagnosis of occupational respiratory allergy is made by a combination of medical history, physical examination, positive methacholine challenge result or bronchodilator responsiveness, determination of IgE-mediated sensitization, and specific inhalation challenge tests as the gold standard. Accurate diagnosis of asthma is the first step to managing OA as shown above. Removal from the causative agent is of central importance for the management of OA. The best strategy to avoid OA is primary prevention, ideally by avoiding the use of and exposure to the sensitizer or substituting safer substances for these agents.

The Medical Gloves Assessment Tool (MGAT): Developing and validating a quantitative tool for assessing the safety and ergonomic features related to medical gloves

BACKGROUND

Medical gloves play a very important role in protecting health care workers and patients. It is very important to pay attention to the safety and ergonomic properties of medical gloves in their protective function.

AIM

To develop a quantitative tool for evaluating the safety and ergonomic properties of the medical gloves.

METHODS

Five hospitals with a total of 185 health care workers participated in the research. The domains and items of the tool were developed based on an expert's panel, interviews with health care workers and a literature review. Face, content and construct validity was used for validation. Reliability was also evaluated using internal consistency.

RESULTS

The final tool included 26 items in six domains, including tactile sensation, dexterity, grip strength, fitting, reliability and hand hygiene. The Cronbach's alpha was 0.82 for the total scale.

CONCLUSION

The final tool had good validity and reliability. The findings of this study led to the development of a comprehensive standard tool that can be used to assess the ergonomic and safety status of medical gloves.

IMPLICATIONS FOR NURSING MANAGEMENT

With this tool, problems related to medical gloves can be identified among nurses, and the necessary interventions can be predicted.

Latex Allergy: Current Status and Future Perspectives

Allergy to natural rubber latex (NRLA) from Hevea brasiliensis is a relevant public health issue, in particular in healthcare workers and groups at risk. Clinical manifestations of NRLA can range from mild skin disorders to life-threatening systemic reactions. Prevention measures remain the gold-standard treatment for patients suffering from NRLA, but the only etiological therapy able to influence the natural history of NRLA is specific desensitization. This review aims to underline the epidemiological, clinical and diagnostic aspects of NRLA, and carries out a complete and wide-ranging review of the current literature on NRLA management and immunotherapy.

New perspectives in bronchial asthma: pathological, immunological alterations, biological targets, and pharmacotherapy

Asthma is the most common, long-lasting inflammatory airway disease that affects more than 10% of the world population. It is characterized by bronchial narrowing, airway hyperresponsiveness, vasodilatation, airway edema, and stimulation of sensory nerve endings that lead to recurring events of breathlessness, wheezing, chest tightness, and coughing. It is the main reason for global morbidity and occurs as a result of the weakening of the immune system in response to exposure to allergens or environmental exposure. In asthma condition, it results in the activation of numerous inflammatory cells like the mast and dendritic cells along with the accumulation of activated eosinophils and lymphocytes at the inflammation site. The structural cells such as airway epithelial cells and smooth muscle cells release inflammatory mediators that promote the bronchial inflammation. Long-lasting bronchial inflammation can cause pathological alterations, viz. the improved thickness of the bronchial epithelium and friability of airway epithelial cells, epithelium fibrosis, hyperplasia, and hypertrophy of airway smooth muscle, angiogenesis, and mucus gland hyperplasia. The stimulation of bronchial epithelial cell would result in the release of inflammatory cytokines and chemokines that attract inflammatory cells into bronchial airways and plays an important role in asthma. Asthma patients who do not respond to marketed antiasthmatic drugs needed novel biological medications to regulate the asthmatic situation. The present review enumerates various types of asthma, etiological factors, and in vivo animal models for the induction of asthma. The underlying pathological, immunological mechanism of action, the role of inflammatory mediators, the effect of inflammation on the bronchial airways, newer treatment approaches, and novel biological targets of asthma have been discussed in this review.

The Role of Immunotherapy and Biologic Treatments in Occupational Allergic Disease

Occupational exposures are estimated to account for 15% to 25% of all adult asthma in the general population. In some cases, workplace allergen exposures can be reduced but not entirely eliminated. Given the potentially significant impact of job change, some workers may choose to continue working in a job in which there is an ongoing occupational allergen exposure. In these cases, a combined approach including personal safety measures, pharmacotherapy, and allergen immunotherapy may result in the best clinical outcomes. This review presents existing evidence for the use of immunotherapy and biologic treatments in occupational allergic disease for various occupational allergens, including wheat flour, mammalian proteins, natural rubber latex, and Hymenoptera venom. There is increasing but modest evidence on beneficial short-term and long-term effects of allergen immunotherapy and safety in worker populations. Available data suggest that allergen immunotherapy can reduce skin and respiratory symptoms and therefore allow workers to continue their current occupation.

Healing effects of natural latex serum 1% from Hevea brasiliensis in an experimental skin abrasion wound model

Background

Dermabrasion is related with mechanical and surgical traumas on the skin; usually topical antiseptics and/or saline have been used for healing. Natural products for wound healing can also be used for abrasions, such as latex from Hevea brasiliensis.

Objective

This study aimed to evaluate the in vitro viability and migratory/proliferative effects of latex serum from H. brasiliensis and to compare with a commercially available standard antiseptic solution and saline in experimental dermabrasion on rats.

Methods

For in vitro evaluation, MTT and scratch assays were used. In vivo testing was performed in 72 rats submitted to dermabrasion, treated with saline, antiseptic, or latex serum. This study evaluated re-epithelialization, neutrophilic infiltration, and the quantification of crust and epidermis.

Results

Latex showed viability at 1% and 0.1% concentrations and migratory/proliferative activity at 0.01% concentrations. The re-epithelialization was highest in latex group on 7th day. The latex group displayed lower thickness of crusts and greater extent of epidermal layers. The latex and antiseptic groups showed increases of myeloperoxidase levels on the 2nd day and showed important reductions from the 7th day.

Study limitations

Acute superficial wound model in rats and non-use of gel-cream (medium) without latex.

Conclusion

In conclusion, non-toxic latex stimulated migration/proliferation of keratinocytes in vitro and significantly accelerated wound healing in animal excoriation models compared to chlorhexidine or saline.

Anisakis Sensitization in the Croatian fish processing workers: Behavioral instead of occupational risk factors?

We undertook the first study systematically evaluating the risk of Anisakis-sensitization in Croatian fish-processing workers and potential genetic susceptibility to anisakiasis. Anti-Anisakis IgE seroprevalence and risk factors for 600 employees of Croatian fish processing facilities and 466 blood donor controls, were assessed by indirect ELISA targeted with: recombinant Ani s 1 and Ani s 7 allergens, an Anisakis crude extract, the commercial ImmunoCAP kit, and questionnaires. Genetic susceptibility to anisakiasis was evaluated by genotypisation of human leukocytes alleles (HLA). Anti-Anisakis seropositive and a fraction of negative subjects were also assessed by ELISA and Western Blot (WB) for IgG seroprevalence to Trichinella spp. Overall, the observed anti-Anisakis seroprevalence inferred by indirect ELISA was significantly higher in fish processing workers (1.8%, 95% CI 0.9–3.3%) compared to the controls (0%, 0–0.8%). Seven out of 11 Ani s 1 and Ani s 7-positives and none of selected 65 negative sera, tested positive on whole-Anisakis extract (ImmunoCAP), whereas Anisakis crude extract ELISA detected 3.9% (2.4–6.0%) seropositives in fish processing workers, three (14%) of which showed IgE reactivity to milk proteins. The highest risk associated with Anisakis-sensitization among workers was fishing in the free time, rather than any of attributes related to the occupational exposure. Although no association was observed between anti-Anisakis seropositivity and wearing gloves or protective goggles, the majority of workers (92%) wore protective gloves, minimizing the risk for Anisakis sensitization via skin contact. Six HLA alleles within DRB1 gene were significantly associated with seropositivity under dominant, allelic or recessive models. All sera confirmed negative for anti-Trichinella spp. IgG. The study exhaustively covered almost all marine fish processing workers in Croatia, reflecting real-time Anisakis sensitization status within the industry, already under the influence of wide array of allergens.

Anisakiasis is a human disease caused by ingestion of live Anisakis spp. larvae by raw seafood. Fish processing and aquaculture workers (approximately 60 million people world-wide) are at occupational risk of becoming sensitized to Anisakis. This is the first study systematically evaluating the risk of Anisakis-sensitization in Croatian fish-processing workers and potential genetic susceptibility to anisakiasis in the analysed population. Observed seroprevalence was significantly higher in fish processing workers (1.8%) compared to the controls (0%). Surprisingly, the highest risk associated with Anisakis-sensitization among workers was fishing in their free time, rather than any of attributes related to the occupational exposure. While no association was observed between anti-Anisakis seropositivity and wearing gloves or protective goggles, the majority of workers (92%) wore protective gloves, minimizing the risk for Anisakis sensitization via skin contact. Additionally, seroprevalence to another important food-borne helminth, Trichinella spp. assessed in all Anisakis-positive subjects showed to be negative. Almost all marine fish processing workers in Croatia were part of this research, reflecting real-time Anisakis-sensitization status within the industry. This sets a baseline for the future tracking of sensitization in the sector already under the influence of wide array of allergens.

Potential Applications of Guayulins to Improve Feasibility of Guayule Cultivation

Guayule (Parthenium argentatum Gray) is an interesting alternative and renewable source of rubber/latex which has been used in the past. Guayule rubber and latex products are not available in the market largely because the raw material cost is higher than the current sources produced in South-East Asia and other tropical countries (Hevea brasiliensis). Guayule contains many other compounds whose joint exploitation could make guayule cultivation profitable, especially in semi-desert areas where cultivation of other crops is difficult or impossible. Guayulins A–D, sesquiterpene esters, appear to have some commercial promise. Despite being accumulated in relatively high concentrations (its majority representative, guayulin A, can account for up to 13.7% of the resin content of this plant, which itself ranges from 6%–12%), guayulins have received little direct attention from scientists. This review presents the current knowledge about the activity of these compounds and, based on known activities of similar compounds from other species, potential uses as fungicides, miticides and insecticides are suggested.

Dermatitis among workers in Ontario: results from the Occupational Disease Surveillance System

Objectives

Dermatitis is the most common occupational skin disease, and further evidence is needed regarding preventable risk factors. The Occupational Disease Surveillance System (ODSS) derived from administrative data was used to investigate dermatitis risk among industry and occupation groups in Ontario.

Methods

ODSS cohort members were identified from Workplace Safety and Insurance Board (WSIB) accepted lost time claims. A case was defined as having ≥2 dermatitis physician billing claims during a 12-month period within 3 years of cohort entry. A 3-year look-back period prior to cohort entry was used to exclude prevalent cases without a WSIB claim. Workers were followed for 3 years or until dermatitis diagnosis, age 65 years, emigration, death or end of follow-up (31 December 2016), whichever occurred first. Age-adjusted and sex-adjusted Cox proportional hazard models estimated HRs and 95% CIs. The risk of dermatitis was explored using a job exposure matrix that identifies exposure to asthmagens, many of which also cause contact dermatitis.

Results

Among 597 401 workers, 23 843 cases of new-onset dermatitis were identified. Expected elevated risks were observed among several groups including furniture and fixture industries, food and beverage preparation and chemicals, petroleum, rubber, plastic and related materials processing occupations and workers exposed to metal working fluids and organic solvents. Decreased risk was observed among farmers, nurses and construction industries, and occupations exposed to latex and indoor cleaning products.

Conclusions

ODSS can contribute to occupational dermatitis surveillance in Ontario by identifying occupational groups at risk of dermatitis that can then be prioritised for prevention activities.

Allergen-specific IgE to recombinant latex allergens in occupational allergy diagnostics

Objectives

Specific challenge tests (SICs) are considered reference tests for allergic occupational diseases diagnosis. However, in numerous cases, SICs cannot be carried out in the diagnosis of allergy to latex due to the risk of generalized reactions. The aim of the study was to evaluate the usefulness of sIgE determination to recombinant latex allergens in diagnostics of occupational respiratory allergy.

Materials and Methods

The study group comprised 44 healthcare workers (HCW) suspected of suffering from occupational respiratory allergy to latex (they underwent a physical examination, skin‐prick tests (SPTs) to common and latex allergens, spirometry and SIC) and 17 controls not occupationally exposed to latex, with a positive sIgE against latex. Each serum was tested for allergen‐specific IgE to aeroallergens, latex, eight recombinant latex allergens and CCD‐markers.

Results

Specific IgE against Hev b5, 6.01, and 6.02 were significantly more frequently detected in HCWs and their mean serum levels were higher compared with the control group. In 26 HCWs with occupational asthma (OA), sensitization to Hev b5, Hev b6.01, Hev b6.02 was significantly more frequent than in 18 HCWs with work‐exacerbated asthma (WEA); they had positive results SPT to latex significantly more frequently in comparison with subjects with WEA.

Conclusions

Test for recombinant latex allergens is much more accurate in recognition of latex allergy than test for latex extract, which seems to produce false‐positive results in patients with pollen allergy. The measurements of sIgE against recombinant latex allergens Hev b 6.01, 6.02, 5, and 8 are useful in differentiating OA from WEA.

Association of hand and arm disinfection with asthma control in US nurses

OBJECTIVES

To investigate the association between occupational exposure to disinfectants/antiseptics used for hand hygiene and asthma control in nurses.

METHODS

In 2014, we invited female nurses with asthma drawn from the Nurses' Health Study II to complete two supplemental questionnaires on their occupation and asthma (cross-sectional study, response rate: 80%). Among 4055 nurses (mean age: 59 years) with physician-diagnosed asthma and asthma medication use in the past year, we examined asthma control, as defined by the Asthma Control Test (ACT). Nurses were asked about the daily frequency of hand hygiene tasks: 'wash/scrub hands with disinfectants/hand sanitizers' (hand hygiene) and 'wash/scrub arms with disinfecting products' (surrogate of surgical hand/arm antisepsis). Analyses were adjusted for age, race, ethnicity, smoking status and body mass index.

RESULTS

Nurses with partly controlled asthma (ACT: 20-24, 50%) and poorly controlled asthma (ACT ≤19, 18%) were compared with nurses with controlled asthma (ACT=25, 32%). In separate models, both hand and arm hygiene were associated with poorly controlled asthma. After mutual adjustment, only arm hygiene was associated with poorly controlled asthma: OR (95% CI) for <1 time/day, 1.38 (1.06 to 1.80); ≥1 time/day, 1.96 (1.52 to 2.51), versus never. We observed a consistent dose-response relationship between frequency of arm hygiene tasks (never to >10 times/day) and poor asthma control. Associations persisted after further adjustment for surfaces/instruments disinfection tasks.

CONCLUSIONS

Frequency of hand/arm hygiene tasks in nurses was associated with poor asthma control. The results suggest an adverse effect of products used for surgical hand/arm antisepsis. This potential new occupational risk factor for asthma warrants further study.

The potential of component-resolved diagnosis in laboratory diagnostics of allergy

The initial laboratory approach in the diagnosis of allergies is to detect the type of allergic reaction, i.e. whether the patient’s allergy is mediated by immunoglobulin E (IgE) or not. For this purpose, the concentration of total serum IgE (tIgE) and specific IgE (sIgE) are determined. Progress in laboratory diagnostics is the use of component-resolved diagnosis (CRD) which implies determination of sIgE against purified native and recombinant allergenic molecules. Component-resolved diagnosis is used in laboratory practice as singleplex and multiplex assays. The choice of allergen for singleplex assay is based on anamnesis, clinical findings of a patient and on skin prick test results. Multiplex-microarray assays simultaneously determine multiple sIgE’s against numerous allergens. The goal of CRD is to distinguish the true allergens from the cross-reactive allergen molecules. Component-resolved diagnosis allows predicting the risk of severe symptoms, as well as anticipating the development of allergies. Thus, determination of sIgE against allergenic components may significantly improve current diagnostics of allergy. Since this method is applied in laboratory practice just a few years, it is necessary to acquire new knowledge and experience, to establish good co-operation between specialist in medical biochemistry and laboratory medicine and the specialist allergologist, so that the method can be applied in a rational manner. Component-resolved diagnosis will significantly improve the diagnostics of IgE-mediated allergy in the future. The aim of this article is to present potentials of CRD in the laboratory diagnostics of allergy mediated by IgE.

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.

Addressing Molecular Diagnosis of Occupational Allergies

PURPOSE OF REVIEW

Numerous clinically relevant allergenic molecules enhance the performance of specific (s) IgE tests and improve the specificity of allergy diagnosis. This review aimed to summarize our current knowledge of the high-molecular-weight allergens involved in the development of occupational asthma and rhinitis and to critically analyze the contribution of component-resolved diagnosis in the management of these conditions.

RECENT FINDINGS

There is a lack of standardization and validation for most available extracts of occupational agents, and assessment of sIgE reactivity to occupational allergen components has been poorly investigated, with the notable exception of natural rubber latex (NRL) and wheat flour. In the case of NRL, the application of recombinant single allergens and amplification of natural extracts with stable recombinant allergens improved the test sensitivity. IgE-sensitization profile in patients with baker's asthma showed great interindividual variation, and extract-based diagnostic is still recommended. For other occupational allergens, it remains necessary to evaluate the relevance of single allergen molecules for the sensitization induced by occupational exposure. Progress has been made to characterize occupational allergens especially NRL and wheat, although there is still an unmet need to increase the knowledge of occupational allergens, to include standardized tools into routine diagnostic, and to evaluate their usefulness in clinical practice.

Animal models of asthma: utility and limitations

Clinical studies in asthma are not able to clear up all aspects of disease pathophysiology. Animal models have been developed to better understand these mechanisms and to evaluate both safety and efficacy of therapies before starting clinical trials. Several species of animals have been used in experimental models of asthma, such as Drosophila, rats, guinea pigs, cats, dogs, pigs, primates and equines. However, the most common species studied in the last two decades is mice, particularly BALB/c. Animal models of asthma try to mimic the pathophysiology of human disease. They classically include two phases: sensitization and challenge. Sensitization is traditionally performed by intraperitoneal and subcutaneous routes, but intranasal instillation of allergens has been increasingly used because human asthma is induced by inhalation of allergens. Challenges with allergens are performed through aerosol, intranasal or intratracheal instillation. However, few studies have compared different routes of sensitization and challenge. The causative allergen is another important issue in developing a good animal model. Despite being more traditional and leading to intense inflammation, ovalbumin has been replaced by aeroallergens, such as house dust mites, to use the allergens that cause human disease. Finally, researchers should define outcomes to be evaluated, such as serum-specific antibodies, airway hyperresponsiveness, inflammation and remodeling. The present review analyzes the animal models of asthma, assessing differences between species, allergens and routes of allergen administration.

Occupational contact urticaria and protein contact dermatitis: causes and concomitant airway diseases

BACKGROUND

Contact urticaria (CU) and protein contact dermatitis (PCD) are mainly induced by an immediate, IgE-mediated immunological mechanism. Immediate sensitization is also linked to asthma and/or allergic rhinitis.

OBJECTIVES

To report causes of work-induced CU and PCD, and to evaluate the occurrence of concomitant airway diseases.

METHODS

We retrospectively reviewed the patient files of cases diagnosed with CU or PCD at the Finnish Institute of Occupational Health during 1995-2011. We obtained data on occupation, exposures, clinical and immunological test results, and diagnosed occupational skin and respiratory diseases.

RESULTS

Altogether, 291 cases of occupational CU or PCD were diagnosed during the study period. The most common causes were flour, cow dander, natural rubber latex and acid anhydrides. Concomitant occupational asthma caused by the same agent as the skin disease was detected in 60 patients (21%), and occupational rhinitis was detected in 111 patients (38%).

CONCLUSIONS

Almost half of the patients (46%) with occupational CU and PCD had concomitant occupational airway disease. Patients with CU/PCD should always be asked about respiratory symptoms, and preventive measures at the workplace should include protection of both the skin and the airways.