Mold Sensitization in Asthmatic and Non-asthmatic Subjects Diagnosed with Extract-Based Versus Component-Based Allergens.

Asthmatic patients are suspected of having a higher risk of mold sensitization. Thus, precise diagnosis of fungal sensitization is important. Mold allergen extracts are difficult to standardize, but component-resolved allergy diagnosis may be an alternative to replace extract-based tests. In this research, asthmatic and non-asthmatic subjects were studied for their sensitization to Aspergillus fumigatus (Asp f), Cladosporium herbarum (Cla h), Penicillium chrysogenum (Pen ch), Alternaria alternata (Alt a), and Aspergillus versicolor (Asp v). Extract-based tests were applied using the skin prick test (SPT) and allergen-specific immunoglobulin E (sIgE). Subjects with extract-based sensitization to Asp f or Alt a were further investigated for sIgE response to recombinant (r) single mold allergens. At least one mold sensitization was found in about 50% of asthmatic and non-asthmatics with the most frequent sensitization to Alt a, followed by Pen ch, Asp f, Cla h, and Asp v. Interestingly, sensitization rate to individual mold species was always higher in asthmatics and was only significant for Pen ch. The component-resolved diagnosis with the sum of rAsp f 1 - rAsp f 4 plus rAsp f 6 matched the extract-based results (SPT and/or sIgE) in 50% of asthmatics and 46% of non-asthmatics, whereas, rAlt a 1 covered 59% of asthmatics and 50% non-asthmatics of extract-based Alt a sensitization. In conclusion, individual fungal sensitization rate was higher in asthmatics compared to non-asthmatics. Extract-based tests, especially SPTs, were most sensitive, but component-based tests covered 80% of extract-based serological sensitization to Alternaria and Aspergillus.

Workplace exposure to wood dust and the prevalence of wood-specific sensitization.

Wood is processed worldwide, and occupational exposure to wood dust is affecting millions of workers. Studies have identified wood dust as a risk factor for non-malignant respiratory diseases consistent with both an allergic and a non-allergic origin. This paper summarizes our current knowledge on the importance of specific sensitization among subjects occupationally exposed to wood dust. Specific sensitization to wood dust exists, but is probably of minor importance for most wood species. In order to move the research field forward increased focus on more standardized tools for specific IgE (sIgE) diagnostics is needed and more specific tools are necessary to identify clinical relevant cases of wood dust sensitization. Moreover epidemiological studies on the occurrence of sIgE-mediated sensitization in different populations of woodworkers are needed.

Rare and new occupational inhalant allergens.

Occupational airway diseases induced by the inhalation of allergens at workplaces have become common, but the inducing substances are diverse and their pathomechanisms are not always clear. Only few allergens were studied in detail (like wheat flour dust and natural rubber latex) and most of the occupational airway sensitizers were documented only as case reports. In this review rare and exotic occupational Type I-aeroallergens according to their workplace application area (e.g., production of dough and bakery products, handling with decorative and economic plants, wood processing, fish-, shellfish-processing and fish breeding) are described.

Quantification of obeche wood allergen: Development of a sensitive sandwich-ELISA for occupational exposure assessment.

Obeche wood is a prominent cause of allergic occupational asthma. To reduce the risk of immunoglobulin E (IgE)-mediated sensitization it is important to assess airborne obeche wood allergen concentrations at exposed workplaces. Therefore, a highly sensitive obeche wood allergen immunoassay was developed and applicability was proven on airborne passive dust samples in Spanish wood workshops. Obeche wood sandwich enzyme-linked immunosorbent assay (ELISA) polyclonal antibodies (pAbs) were developed. Test specificity was verified by different wood and mold extracts. Obeche wood allergen monitoring was conducted in four Spanish wood workshops, including wood-dust-exposed and nonexposed areas inside and outside the workplaces, as well as controls. Dust was collected with electrostatic dust collectors (EDC). Measuring range of the obeche wood sandwich-ELISA was between 36 pg/ml and 1.6 µg/ml. The test system showed only marginal reactivity to other hardwoods and no reactivity to softwoods and molds. Obeche allergen was detected in all EDC from workplaces. The highest concentration was measured in the workshop with the longest obeche wood exposure (geometric mean [GM]: 7548 µg/m2); shorter obeche wood processing periods resulted in lower amounts of allergen (GM: 29 µg/m2). Obeche wood allergen transfer from exposed workplaces to nonexposed areas inside and outside the workshop was assessed. In control EDC from nonexposed facilities/homes no obeche wood allergen was found. The new obeche wood sandwich-ELISA is a valid tool to quantify obeche allergen exposure. Evidence indicates it will be possible to monitor obeche allergen exposure during different processes, as well as transfer effects in nonexposed areas.

How to diagnose mould allergy? Comparison of skin prick tests with specific IgE results.

BACKGROUND: Diagnosis of mould allergy is complicated due to the heterogeneity of the test material and the decrease in the number of commercial mould skin test solutions that are currently available. OBJECTIVES: The aim of this study was to compare skin prick tests (SPT) from different manufacturers to one another and concurrently with sIgE tests for Aspergillus fumigatus (Asp f), Cladosporium herbarum (Cla h), Penicillium chrysogenum (Pen ch), Alternaria alternata (Alt a) and Aspergillus versicolor (Asp v) to ascertain a feasible diagnostic procedure for mould sensitization. METHODS: In this multi-centre study, 168 patients with mould exposure and/or mould-induced respiratory symptoms were included. Mould SPT solutions were analysed biochemically and tested in duplicate on patients' arms. Specific IgE (sIgE) concentrations to corresponding mould species and mould mix (mx1) were measured by ImmunoCAP. SPTs in accordance with one another and with sIgE were further considered. The test efficiency was calculated using receiver-operating characteristic (ROC) analysis. RESULTS: Mould sensitization was more frequently detected by the SPT (90 of 168) than by the sIgE tests (56 of 168). Concordances of double SPT positives were only sufficient (≥ 80%) for environmental allergens, two Asp f and three Alt a SPT solutions, whereas all other mould solutions revealed concordances < 80%. The antigen content of SPT solutions was positively associated with concordant SPT double values as well as with sIgE. Taking sIgE as the 'positive standard', all mould SPT solutions revealed test efficiencies > 80%, but varied up to 20% in sensitivity and positive predictive value with the exception of Alt a. CONCLUSIONS: SPT solutions are sensitive and essential diagnostic tools for the detection of mould sensitization. Our recommendation for diagnosis would be to test at least Alt a, Asp f and Pen ch using SPT and additional sIgE test to mx1.

Monitoring of occupational and environmental aeroallergens-- EAACI Position Paper. Concerted action of the EAACI IG Occupational Allergy and Aerobiology & Air Pollution.

Exposure to high molecular weight sensitizers of biological origin is an important risk factor for the development of asthma and rhinitis. Most of the causal allergens have been defined based on their reactivity with IgE antibodies, and in many cases, the molecular structure and function of the allergens have been established. Significant information on allergen levels that cause sensitization and allergic symptoms for several major environmental and occupational allergens has been reported. Monitoring of high molecular weight allergens and allergen carrier particles is an important part of the management of allergic respiratory diseases and requires standardized allergen assessment methods for occupational and environmental (indoor and outdoor) allergen exposure. The aim of this EAACI task force was to review the essential points for monitoring environmental and occupational allergen exposure including sampling strategies and methods, processing of dust samples, allergen analysis, and quantification. The paper includes a summary of different methods for sampling and allergen quantification, as well as their pros and cons for various exposure settings. Recommendations are being made for different exposure scenarios.

Biochemical and immunological analysis of mould skin prick test solution: current status of standardization.

BACKGROUND: Sensitization prevalence to moulds reached from less than 10% in the general population to more than 25% in atopic and/or asthmatic subjects. To diagnose IgE-mediated mould sensitization, skin prick test (SPT) and specific IgE (sIgE) measurement are recommended. However, concordance of SPT and sIgE results is often less than 50% and standardization of the extracts is required to achieve reliable test results. OBJECTIVE: The aim of our study was to analyse mould SPT solutions (SPTs) with respect to quantity and quality of protein, antigen and human IgE-binding content as a prerequisite for further in vivo studies. METHODS: Commercial SPTs of Alternaria alternata, Aspergillus fumigatus, Cladosporium herbarum and Penicillium chrysogenum from six manufacturers as well as two in-house extracts from Aspergillus versicolor were investigated. Protein-, antigen- and IgE-binding contents were quantified by Bradford assay, sandwich ELISA and IgE-ImmunoCAP-inhibition tests. Protein composition and IgE and IgG binding were analysed by SDS-PAGE and immunoblotting, respectively. RESULTS: Median protein concentrations were similar in all mould SPT extracts (90-110 µg/mL). In contrast, antigen contents and IgE-binding capacity showed a high variability with median antigen values from 4 to 118 µg/mL and IgE inhibition results between 30 to 95%. Whereas almost all SPTs of A. alternata and A. versicolor showed complete sIgE inhibition with mean values > 80%, only three extracts for A. fumigatus, two extracts for C. herbarum and none of the tested extracts for P. chrysogenum exceeded 50% sIgE reduction. Quantitative amounts of protein, antigenic and IgE-binding structures were not comparable with the quality of the corresponding protein or immunoblot pattern, with the exception of A. alternata SPTs. CONCLUSIONS AND CLINICAL RELEVANCE: Commercially available mould SPT extracts showed high variability raising the question of comparability and reliability of SPT results. Possible consequences for diagnostic test outcome will be investigated in the next step.

[Workplace-related respiratory allergies. Current developments]. / Inhalationsallergien am Arbeitsplatz. Aktuelle Entwicklungen.

It is common that the inhalation of occupational allergens induces occupational airway diseases, but the inducers are diverse and complex, and the pathomechanism of the disease is not clear in every case. Only few allergens have been studied in detail (e.g., wheat flour and natural rubber latex), and most of the occupational airway sensitizers have only been documented as case reports. This review describes occupational type I aeroallergens according to their source (plant, animal, microbial, and chemical) and workplace application area. New aspects on the diagnosis and legal preventive regulations for occupational allergic airway diseases are described.

Impact of cross-reactive carbohydrate determinants on wood dust sensitization.

BACKGROUND: Occupational wood dust exposure can induce allergy and may be one cause of respiratory health problems among woodworkers. OBJECTIVE: The objective was to determine the prevalence and quantitative level of specific immunoglobulin E (sIgE) to beech and pine wood in exposed workers. Wood sensitization was specified with regard to cross-reactivity and was correlated to the reported symptoms. METHODS: Danish workers (n=701) were investigated for sIgE to beech and pine. Wood samples from workplaces were analysed and coupled to ImmunoCAPs. Workers sensitized to wood were tested for cross-reactive carbohydrate determinants (CCDs) and environmental allergens. IgE binding was specified for glycogenic vs. proteinogenic epitopes by inhibition tests. RESULTS: The prevalence of wood sensitization among all workers was 3.7%. There was no association between sensitization prevalence or sIgE concentrations and self-reported allergic symptoms. Beech- and pine-sensitized workers showed a high prevalence of CCD sensitization (73%). However, workers with a single sensitization to wood had no sIgE to CCDs. Specifying IgE epitopes demonstrated that sera of workers reporting allergic symptoms recognized proteinogenic IgE-epitopes on wood allergens, whereas workers without allergic symptoms had primarily sIgE-epitopes to glycogenic structures. Although 96% of the wood-sensitized workers were atopic, no significant correlation was found between wood sensitization and sIgE to beech and birch pollen, but an association was found between sIgE against CCDs and pine pollen. CONCLUSION: Sensitization prevalence to beech and pine wood measured by tailored ImmunoCAPs was not correlated to allergic symptoms. We recommend the application of CCD tools to assess the relevance of individual wood sensitization.

Natural rubber latex and chestnut allergy: cross-reactivity or co-sensitization?

BACKGROUND: Chestnut and natural rubber latex (NRL) allergy are often associated in the latex-fruit syndrome. AIM OF THE STUDY: To establish whether the concurrent NRL and chestnut IgE antibody reactivity are the results of co-sensitization or cross-reactivity. METHODS: Sera from 19 patients with chestnut- and NRL-specific IgE were selected and tested for reactivity with recombinant (r) latex allergens. Cross-reactivity was explored by IgE-inhibition experiments using chestnut or NRL allergens as solid phase on ImmunoCAP. RESULTS: IgE-antibodies were detected to rHev b 6.01 (prohevein) in 58% of the sera, to rHev b 5 in 32%, to rHev b 12 in four of 13 sera, to rHev b 7.02 and rHev b 11 in four, and to rHev b 1 in two of 19 sera. rHev b 8-IgE antibodies were found in nine sera (47%), whereas six displayed mono-sensitization to rHev b 8 with regard to our test panel. Three of 16 sera showed IgE to cross-reactive carbohydrate determinants. In most sera recognizing rHev b 5 and/or rHev b 6.01 as major allergens the IgE-reactivity to NRL remained unaffected by chestnut extract and chestnut-IgE remained unaffected by NRL extract. Conversely, in sera with rHev b 8 as dominant allergen IgE-binding to NRL was nearly completely inhibited by chestnut and vice versa. IgE-binding to rHev b 8 was abolished by chestnut extract. CONCLUSIONS: Although patients have concomitant IgE antibody reactivity to chestnut and NRL, cross-reactivity could be demonstrated mainly in those patients with IgE to Hev b 8 (profilin) from NRL.

Identification of an obeche (Triplochiton scleroxylon) wood allergen as a class I chitinase.

BACKGROUND: Wood dust is known to cause allergic occupational asthma and obeche (Triplochiton scleroxylon) is a prominent exponent in this field. However, the knowledge about wood allergens is still limited. The aim of this study was to identify and characterize obeche wood allergens. METHODS: Obeche extracts were prepared from freshly ground in comparison to 7 years stored wood dust and investigated by Sodium dodecyl sulfate-polyacrylamid gel electrophoresis, enzyme-linked allergosorbent test and immunoglobulin (Ig)E-immunoblot. Allergens were detected by specific IgE of seven obeche allergic patients' sera and protein analysis was performed by mass spectrometry. Cross-reactivity was demonstrated by ImmunoCAP-inhibition with sera of seven obeche and four latex-allergic patients. RESULTS: Obeche extracts showed different protein pattern and IgE-binding capacities depend on the age of the wood dust. A 38 kDa protein was identified as major obeche wood allergen, detected by six of seven (85%) obeche allergic patients' sera and was entitled as Trip s 1. Trip s 1 is homologous to plant class I chitinases and exhibited enzyme activity demonstrated by chitinolysis. Co-recognition or cross-reactivity of Trip s 1 according to structural similarity was seen in sera of latex allergic patients. IgE inhibition studies with obeche as solid phase and Trip s 1 and latex hevein as inhibitor demonstrated that Trip s 1 was a more effective inhibitor in obeche as well as in latex allergic patients' sera. CONCLUSIONS: Trip s 1 is a new obeche wood allergen of the plant class I chitinase family. This finding may explain the dominant role of obeche in sensitization against wood dust.

Cross-reactivity between obeche wood (Triplochiton scleroxylon) and natural rubber latex.

BACKGROUND: Several studies have shown that allergy to natural rubber latex is associated with cross reactivity to other plants. We have investigated a possible cross reactivity with a tree belonging to the Sterculiaceae family, Tryplochiton scleroxylon, in a patient allergic to obeche wood, that began to suffer symptoms of allergy in contact with latex. METHODS: Determinations of specific IgE by CAP to obeche, natural rubber latex (NRL) and recombinant allergens of latex were done. Immunoblotting was performed to study allergens detected by serum of our patient. CAP-inhibition methods were used to study cross-reactive between NRL and obeche wood. RESULTS: In obeche extract, 4 bands were found of an apparent molecular weight of 18, 38, 75 and 199 kDa. In NRL extract the allergens have a molecular weight around 18, 21, 32, 38, 60, 70 and 199 kDa. IgE to latex was almost completely inhibited (96%) by the obeche extract in CAP-inhibition studies. Using obeche extract as inhibitor, IgE binding to native hevein (nHevb 6.02) was reduced by 25%. CONCLUSIONS: The results obtained in CAP-inhibition demonstrate the existence of cross-reactivity between proteins in NRL and obeche wood. In our patient, a band of apparent molecular weight of 38 kDa could be the most important allergen.