[Farmer's lung antigens in Germany]

Recent studies suggest that besides the long-known farmer's lung antigen sources Saccharopolyspora rectivirgula (Micropolyspora faeni), Thermoactinomyces vulgaris, and Aspergillus fumigatus, additionally the mold Absidia (Lichtheimia) corymbifera as well as the bacteria Erwinia herbicola (Pantoea agglomerans) and Streptomyces albus may cause farmer's lung in Germany. In this study the sera of 64 farmers with a suspicion of farmer's lung were examined for the following further antigens: Wallemia sebi, Cladosporium herbarum, Aspergillus versicolor, and Eurotium amstelodami. Our results indicate that these molds are not frequent causes of farmer's lung in Germany.

Development and application of mold antigen-specific enzyme-linked immunosorbent assays (ELISA) to quantify airborne antigen exposure

The aim of our study was to develop specific enzyme-linked immunosorbent assays (ELISAs) and apply these to assess mold antigen exposure in composting plants. Sandwich ELISAs based on polyclonal antibodies to Aspergillus fumigatus (Af), Penicillium chrysogenum (Pc), and Cladosporium herbarum (Ch) antigens were developed and validated. Reactivity to 18 different mold species was tested. To optimize extraction procedure, inhalable dust samples taken by a parallel sampler were extracted with or without homogenization. In 31 composting plants stationary pumps were installed at 4 sites to collect 124 inhalable dust samples. The newly developed ELISAs were used in addition to an anti β-1,3-glucan ELISA to quantify mold antigens. The Cladosporium ELISA showed less than 0.04% reactivity to extracts from other fungal genera, while the Af ELISA demonstrated a reactivity of up to 3.6% and the Pc ELISA reacted up to 11% to other mold species. Extraction of parallel sampled filters gave higher antigen amounts with homogenization. The increase was highest for Pc-antigens, followed by Af-antigens, and lowest for Ch-antigens. Mean lower detection limits of homogenized inhalable dust samples were 5 ng/m(3) (Af), 0.6 ng/m(3) (Pc), 0.2 ng/m(3) (Ch), and 0.6 ng/m(3) (β-1,3-glucan). The ELISAs were able to detect antigens in 43% (Af), 37% (Pc), 94% (Ch), or 100% (β-1,3-glucan) of the 124 airborne dust samples. Inhalable dust, β-1,3-glucan, and Af-, Pc-, and Ch-antigen concentrations were significantly correlated. The newly developed mold antigen ELISAs are thus able to measure airborne exposure levels in composting plants and differentiate between distinct fungi genera.

Multiple wheat flour allergens and cross-reactive carbohydrate determinants bind IgE in baker's asthma

BACKGROUND

Several wheat flour allergens relevant to baker's asthma have been identified in the last 25 years. The aim of this study was to determine the frequency of sensitization to these allergens in German bakers.

METHODS

Using recombinant DNA technology, the following wheat flour allergens were cloned, expressed in Escherichia coli and purified: five subunits of the wheat α-amylase inhibitors (WTAI-CM1, WTAI-CM2, WTAI-CM3, WDAI-0.19 and WMAI-0.28), thioredoxin, thiol reductase or 1-cys-peroxiredoxin homologues, triosephosphate-isomerase, αβ-gliadin, serpin, glyceraldehyde-3-phosphate-dehydrogenase, a nonspecific lipid transfer protein (nsLTP), dehydrin, profilin and peroxidase. In addition, ImmunoCAPs with the recombinant allergen ω-5-gliadin and two cross-reactive carbohydrate determinants (CCDs), horse radish peroxidase (HRP) and the N-glycan of bromelain (MUXF), were used. Specific IgE was measured in wheat flour-positive sera from 40 German bakers with work-related asthma/rhinitis and 10 controls with pollinosis.

RESULTS

Thirty bakers (75%) had IgE to at least one of the 19 single allergens. Most frequent was IgE to WDAI-0.19, HRP and MUXF (25% each), followed by WTAI-CM1 (20%), thiol reductase (16%), WTAI-CM3 (15%), WTAI-CM2 and thioredoxin (12.5%), WMAI-28, triosephosphate-isomerase, αβ-gliadin (10%), 1-cys-peroxiredoxin (7.5%), dehydrin, serpin, glyceraldehyde-3-phosphate-dehydrogenase (5%), ω-5-gliadin, nsLTP and profilin (2.5%). Fifteen bakers (38%) had IgE to any α-amylase inhibitor and 12 (30%) to at least one CCD. The controls reacted exclusively to CCDs (80%), profilin (60%), thioredoxin (30%), triosephosphate isomerase and nsLTP (10%).

CONCLUSIONS

The single allergen sensitization profiles obtained with 17 recombinant wheat flour allergens and two CCDs revealed no major allergen for German bakers. The highest frequencies were found for α-amylase inhibitors and CCDs.

Allergic asthma after flour inhalation in subjects without occupational exposure to flours: an experimental pilot study

OBJECTIVE

Cross-reactivity between grass pollen and grain flour allergens is well known, but their significance in apprentice bakers with primary sensitization to grass pollen is not known.

METHODS

Twenty-five subjects with mild asthma (most of them with hay fever), but without prior occupational flour exposure, underwent standardized experimental inhalation challenges with placebo and wheat and rye flours in randomized order on three consecutive days. Sensitization to flours and environmental allergens was assessed by skin prick tests and specific IgE antibodies in sera. IgE inhibition experiments were performed with wheat and rye flours as solid phases, and grass and tree pollen as inhibitors.

RESULTS

Five subjects experienced a positive reaction after flour inhalation (responders), whereas 20 subjects did not show such a reaction (non-responders). All responders showed sensitizations to flours, whereas only 25% of the non-responders demonstrated the same sensitization. Specific IgE concentrations to flours, but also to grass and tree pollen, were higher in responders. Inhibition experiments demonstrated cross-reactivity between flours and grass or tree pollen, with higher inhibition rates in responders.

CONCLUSIONS

Subjects with pronounced sensitizations to grass or tree pollen, but without prior occupational exposure to flours, may experience both sensitization and allergic asthmatic reactions to flours due to cross-reactive grass and tree pollen allergens.

Development of an enzyme-linked immunosorbent assay for the detection of human calretinin in plasma and serum of mesothelioma patients

Background

Calretinin is one of the well-established immunohistochemical markers in the diagnostics of malignant mesothelioma (MM). Its utility as a diagnostic tool in human blood, however, is scarcely investigated. The aim of this study was to develop an enzyme-linked immunosorbent assay (ELISA) for human calretinin in blood and to assess its usefulness as a potential minimally invasive diagnostic marker for MM.

Methods

Initially, attempts were made to establish an assay using commercially available antibodies and to optimize it by including a biotin-streptavidin complex into the assay protocol. Subsequently, a novel ELISA based on polyclonal antibodies raised in rabbit immunized with human recombinant calretinin was developed. The assay performance in human serum and plasma (EDTA/heparin) and the influence of calcium concentrations on antibody recognition were studied. Stability of spiked-in calretinin in EDTA plasma under different storage conditions was also examined. In preliminary studies serum and plasma samples from 97 healthy volunteers, 35 asbestos-exposed workers, and 42 MM patients were analyzed.

Results

The mean detection range of the new ELISA was 0.12 to 8.97 ng/ml calretinin. The assay demonstrated markedly lower background and significantly higher sensitivity compared to the initially contrived assay that used commercial antibodies. Recovery rate experiments confirmed dependence of calretinin antibody recognition on calcium concentration. Calcium adjustment is necessary for calretinin measurement in EDTA plasma. Spiked-in calretinin revealed high stability in EDTA plasma when stored at room temperature, 4°C, or after repeated freeze/thaw cycles. Median calretinin values in healthy volunteers, asbestos workers, and MM patients were 0.20, 0.33, and 0.84 ng/ml, respectively (p < 0.0001 for healthy vs. MM, p = 0.0036 for healthy vs. asbestos-exposed, p < 0.0001 for asbestos-exposed vs. MM). Median values in patients with epithelioid and biphasic MM were similar. No influence of age, gender, smoking status, or type of medium (plasma/serum) on calretinin values was found.

Conclusions

The novel assay is highly sensitive and applicable to human serum and plasma. Calretinin appears to be a promising marker for the blood-based detection of MM and might complement other markers. However, further studies are required to prove its usefulness in the diagnosis of MM patients.

[Diagnostics of occupational type I allergies--comparison of skin prick test solutions from different manufacturers for selected occupational allergens]

BACKGROUND

Reactivity in the skin prick test (SPT) is related to the potency of the SPT solution used. The aim of this study was to compare SPT solutions from different manufacturers for selected occupational allergens.

PATIENTS

All patients suffered from work-related allergic complaints like rhinitis, conjunctivis or asthmatic complaints.

METHODS

125 bakers and 21 subjects exposed to natural rubber latex (NRL) were examined with four flour SPT solutions and two NRL SPT solutions, respectively. By means of the maximum test efficiency (gold standard: specific IgE), the optimal cut-off was determined. Using this cut-off, sensitivities and specificities of the flour and NRL SPT solutions were calculated. Additionally, five SPT solutions for TYROPHAGUS PUTRESCENTIAE (Tp) were tested in two farmers. All SPT solutions were analysed IN-VITRO for protein and antigen content.

RESULTS

IN-VITRO analyses resulted in differences for all SPT solutions depending on the manufacturer. The optimal cut-off for the flour and NRL SPT solutions was a wheal >or= 1.5 mm. Sensitivities of flour SPT solutions ranged from 38 % to 95 %, specificities from 77 % to 98 %. Both NRL SPT solutions reached a sensitivity of 100 % and a specificity of 92 %. SPT results with the different Tp SPT solutions were variable.

CONCLUSION

While both NRL SPT solutions exhibited a fairly good quality, the flour and Tp SPT solutions showed differences between manufacturers. As a rule solutions with higher protein and antigen contents gave better results.

Passive airborne dust sampling with the electrostatic dustfall collector: optimization of storage and extraction procedures for endotoxin and glucan measurement

We recently introduced a passive dust sampling method for airborne endotoxin and glucan exposure assessment-the electrostatic dustfall collector (EDC). In this study, we assessed the effects of different storage and extraction procedures on measured endotoxin and glucan levels, using 12 parallel EDC samples from 10 low exposed indoor environments. Additionally, we compared 2- and 4-week sampling with the prospect of reaching higher dust yields. Endotoxin concentrations were highest after extraction with pyrogen-free water (pf water) + Tween. Phosphate-buffered saline (PBS)-Tween yielded significantly (44%) lower levels, and practically no endotoxin was detected after extraction in pf water without Tween. Glucan levels were highest after extraction in PBS-Tween at 120 degrees C, whereas extracts made in NaOH at room temperature or 120 degrees C were completely negative. Direct extraction from the EDC cloth or sequential extraction after a preceding endotoxin extraction yielded comparable glucan levels. Sample storage at different temperatures before extraction did not affect endotoxin and glucan concentrations. Doubling the sampling duration yielded similar endotoxin and only 50% higher glucan levels. In conclusion, of the tested variables, the extraction medium was the predominant factor affecting endotoxin and glucan yields.

Exposure to flour dust in South African supermarket bakeries: modeling of baseline measurements of an intervention study

INTRODUCTION

Exposure to flour dust has been reported as an important risk factor for allergic respiratory disease among bakery workers. A high prevalence of allergic sensitization and asthma was recently reported in South African supermarket bakeries. The aim of this study was to conduct a detailed exposure assessment of these bakeries so as to provide the baseline for a broader intervention study.

METHODS

A total of 211 full-shift personal samples were collected on randomly selected individuals within five different job categories in 18 bakeries. The samples were analyzed for particulate mass and specific flour dust allergens (wheat, rye, and fungal alpha-amylase). Exposure models were developed using job, bakery size, tasks, and specific ingredients used. Bakery and worker were regarded as random effect components.

RESULTS

Bread bakers had the highest average (geometric mean) exposures (1.33 mg m(-3) flour dust particulate, 13.66 microg m(-3) wheat allergens, and 5.14 microg m(-3) rye allergens). For alpha-amylase allergens, most samples were below the limit of detection for several occupational titles. In the mixed effect models, the significant predictors of elevated exposure to inhalable dust particulate as well as wheat and rye allergen concentrations were large bakery size, bread baking, and use of cereal flours, while tasks such as confectionery work were negatively correlated with these exposure metrics. Weighing tasks and use of premix products were associated with increased exposure to fungal alpha-amylase. A high correlation between particulate dust and wheat (r = 0.84) as well as rye (r = 0.86) was observed, with a much lower correlation between particulate dust and fungal alpha-amylase (r = 0.33). Overall, a low proportion (39%) of bakery stores implemented various control measures to reduce dust exposures in the bakeries.

CONCLUSIONS

This study confirms that current exposure control strategies in supermarket bakery stores are inadequate in reducing dust exposures to protect the health of bakery workers.

Occupational immediate-type asthma and rhinitis due to rhodium salts

BACKGROUND

Whereas platinum salts are well known occupational allergens, rhodium salts have not been identified as inhalative sensitizing substances.

METHODS

A 27-year-old atopic operator of an electroplating plant developed work-related shortness of breath and runny nose with sneezing after exposure to rhodium salts. Quantitative skin prick tests (SPT) and bronchial challenge tests with a dosimeter protocol were performed with quadrupling doses of the sodium chloride salts of rhodium (Na(3)RhCl(6)) and platinum (Na(2)PtCl(6)).

RESULTS

The patient showed positive SPT reactions and positive bronchial immediate-type reactions with rhodium and platinum salts. Sensitivity to rhodium salt was much higher than to platinum salt; the molar concentrations differed by a factor of 256 in SPT and a factor of 16 in bronchial challenges.

CONCLUSIONS

Rhodium salts should be considered as occupational immediate-type allergens.

Allergen content of grass pollen preparations for skin prick testing and sublingual immunotherapy

BACKGROUND

The allergen content of diagnostics and immunotherapeutics is crucial for effective diagnosis and treatment. The aim of this study was to quantify and compare the allergen content of different grass pollen preparations for skin prick testing and sublingual immunotherapy (SLIT).

METHODS

Five skin prick test (SPT) solutions and 10 sublingual immunotherapeutics were analysed for protein and allergen concentration by Bradford assay, inhibition of IgE-binding to Phleum pratense ImmunoCAPs and content of the main allergen Phl p 5 by two-site enzyme immunoassay. In addition, the grass pollen preparations were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting analyses.

RESULTS

Protein concentrations of SPT solutions ranged from 15 to 427 microg/ml, and Phl p 5 concentrations ranged from 0.15 to 18.3 microg/ml. The ranking of SPT solutions concerning Phl p 5 content and IgE inhibition capacity was the same, and the ranking of protein and allergen content was closely correlated (r = 0.9). Protein content of the maintenance doses of the immunotheurapeutics ranged from 5 to 153 microg, Phl p 5 content ranged from 0.2 to 21.6 microg. IgE inhibition capacity of the maintenance doses was closely correlated to their Phl p 5 and protein content. SDS-PAGE and immunoblots confirmed the differences in protein and allergen content.

CONCLUSIONS

Grass pollen preparations for SPT and SLIT varied greatly concerning protein and allergen content. Whereas this result corresponds to previous analyses results of SPT solutions, it was the first comparison of grass pollen immunotherapeutics. For diagnosis and therapy, these differences should be taken into account.

Hypersensitivity pneumonitis caused by occupational exposure to phytase

A 43-yr-old male presented with a 6-month history of episodes of coughing, shortness of breath and fever. He suffered from dyspnoea on minor exertion. The patient worked in a cattle feed factory and noticed that he had more complaints after his working hours. His symptoms could be ascribed to hypersensitivity pneumonitis due to contact with phytase, an enzyme added to cattle feed to strengthen bone and diminish phosphorus excretion. The diagnosis was supported by bibasal lung crackles on physical examination, restrictive ventilatory defect (with decreased diffusion capacity for carbon monoxide), typical radiographical findings, lymphocytosis in bronchoalveolar lavage fluid and a positive exposure test performed at the workplace. Blood examination showed high immunoglobulin G levels to phytase. After treatment and cessation of phytase contact the patient became symptom free and lung function normalised. Phytase should be considered as a cause of occupational hypersensitivity pneumonitis in the animal feed industry.

Comparison of wheat and rye flour solutions for skin prick testing: a multi-centre study (Stad 1)

BACKGROUND

Skin prick testing (SPT) is the basic method for diagnosing IgE-mediated allergies. However, skin reactivity is related to the quality of allergen extracts, which are often poorly defined for occupational allergens.

OBJECTIVE

To compare wheat and rye flour SPT solutions from different producers.

MATERIALS AND METHODS

Standardized SPTs were performed in seven allergy centres with wheat and rye flour solutions from four producers in 125 symptomatic bakers. Optimal cut-off levels for weal sizes were assessed with the Youden Index. Comparisons between SPT results of different solutions were made with flour-specific IgE (sIgE) as the gold standard. Sensitivities, specificities, positive and negative predictive values, and test efficiencies were calculated and compared with McNemar and chi(2)-tests. The influence of the choice of the gold standard (sIgE or challenge) test was examined for 95 subjects. Additionally, SPT solutions were analysed for protein and antigen content.

RESULTS

The optimal cut-off level for all SPT solutions was a weal size of >or=1.5 mm. While differences between wheat and rye flours were small, differences between producers were important. Variability of sensitivities (0.31-0.96), negative predictive values (0.42-0.91), and test efficiencies (0.54-0.90) were higher than variations of specificities (0.74-1.00) and positive predictive values (0.88-1.00). Similar results were obtained when using challenge test results as the gold standard. Variability could be explained by the different antigen contents of the SPT solutions.

CONCLUSION

There is a wide variability of SPT solutions for wheat and rye flour from different producers, mainly with respect to sensitivities, negative predictive values, and test efficiencies. Improvement and standardization of SPT solutions used for the diagnosis of baker's asthma are highly recommended.

A cross-sectional study among detergent workers exposed to liquid detergent enzymes

OBJECTIVES

To investigate sensitisation and respiratory health among workers who produce liquid detergent products and handle liquid detergent enzymes.

METHODS

We performed a cross-sectional study among 109 eligible workers of a detergent products plant. 108 were interviewed for respiratory and allergic symptoms and 106 blood samples were taken from them to examine sensitisation to enzymes. Those sensitised to > or = 1 enzymes were referred for clinical evaluation. Workers and representatives were interviewed to characterise exposure qualitatively and estimate exposure semi-quantitatively. Workers were classified into three exposure groups with varying exposure profiles to enzymes, based on frequency, duration, and level of exposure.

RESULTS

Workers were exposed to proteases, alpha-amylase, lipase and cellulase. The highest exposures occurred in the mixing area. Liquid spills with concentrated enzyme preparations and leakage of enzymes during weighing, transportation and filling were causing workplace contaminations and subsequently leading to both dermal and inhalation exposure for workers. Workers with the highest exposures reported significantly more work-related symptoms of itching nose (prevalence ratio (PR) = 4.2, 95% CI 1.5 to 12.0) and sneezing (PR = 4.0, 95% CI 1.5 to 10.8) and marginally significant more symptoms of wheezing (PR = 2.9, 95% CI 0.9 to 8.7) compared with the least exposed group. Fifteen workers (14.2%) were sensitised to > or = 1 enzymes. A marginally statistically significant gradient in sensitisation across the exposure categories was found (p = 0.09). There was a clinical case of occupational asthma and two others with probable occupational rhinitis.

CONCLUSIONS

Workers exposed to liquid detergent enzymes are at risk of developing sensitisation (14%) and respiratory allergy.

Determinants of asthma phenotypes in supermarket bakery workers

While baker's asthma has been well described, various asthma phenotypes in bakery workers have yet to be characterised. Our study aims to describe the asthma phenotypes in supermarket bakery workers in relation to host risk factors and self-reported exposure to flour dust. A cross-sectional study of 517 supermarket bakery workers in 31 bakeries used a questionnaire, skin prick tests, and specific immunoglobulin E to wheat, rye and fungal alpha-amylase and methacholine challenge testing. The prevalence of probable occupational asthma (OA, 13%) was higher than atopic (6%), nonatopic (6%) and work-aggravated asthma (WAA, 3%) phenotypes. Previous episodes of high exposure to dusts, fumes and vapours causing asthma symptoms were more strongly associated with WAA (OR 5.8, 95% CI 1.7-19.2) than OA (2.8, 1.4-5.5). Work-related ocular-nasal symptoms were significantly associated with WAA (4.3, 1.3-13.8) and OA (3.1, 1.8-5.5). Bakers with OA had an increased odds ratio of reporting adverse reactions to ingested grain products (6.4, 2.0-19.8). OA is the most common phenotype among supermarket bakery workers. Analysis of risk factors contributes to defining clinical phenotypes, which will guide ongoing medical surveillance and clinical management of bakery workers.

Prediction of challenge test results by flour-specific IgE and skin prick test in symptomatic bakers

BACKGROUND

Wheat and rye flours are among the most important allergens causing occupational asthma. Usually, the diagnosis of baker's asthma is based on inhalation challenge tests with flours.

AIMS OF THE STUDY

To evaluate the relevance of flour-specific serum immunoglobulin E (IgE) and skin prick test (SPT) in the diagnosis of baker's asthma and to define flour-specific IgE concentrations and wheal sizes that allow a prediction of the outcome of challenge testing.

METHODS

Bronchial and nasal challenge tests with wheat (rye) flour were performed in 71 (95) symptomatic bakers. Determinations of flour-specific IgE as well as SPTs were performed in all subjects. Analyses included the calculation of sensitivity, specificity, positive (PPV) and negative predictive values (NPV) at different IgE concentrations and different wheal sizes, and receiver-operating characteristics (ROC) plots with the challenge result as gold standard.

RESULTS

Thirty-seven bakers were positive in the challenge with wheat flour, while 63 were positive with rye flour. Depending on the flour-specific IgE concentrations (wheal size), PPV was 74-100% (74-100%) for wheat and 82-100% (91-100%) for rye flour, respectively. The minimal cut-off values with a PPV of 100% were 2.32 kU/l (5.0 mm) for wheat flour and 9.64 kU/l (4.5 mm) for rye flour. The shapes of the ROC plots were similar for wheat and rye flour.

CONCLUSION

High concentrations of flour-specific IgE and clear SPT results in symptomatic bakers are good predictors for a positive challenge test. Challenge tests with flours may be avoided in strongly sensitized bakers.

Development of a two-site enzyme immunoassay based on monoclonal antibodies to measure airborne exposure to (1-->3)-beta-D-glucan

(1-->3)-beta-D-glucan is found in cell walls of some fungi, bacteria and plants. It plays a crucial role in bioaerosol-induced inflammatory reactions. To estimate the level of airborne (1-->3)-beta-D-glucan exposure, a monoclonal antibody-based two-site enzyme immunoassay (mAb-EIA) was developed. The results obtained with the mAb-EIA were compared with the results of a Limulus amoebocyte lysate-based assay for (1-->3)-beta-D-glucan. Three mAbs produced by mouse immunization with bovine serum albumin-conjugated laminarin were enriched by in vitro production in a modular mini-fermenter and affinity purified. Two mAbs were selected for the development of a two-site EIA specific for (1-->3)-beta-D-glucan. Different polysaccharides, fungal and plant seed extracts, and airborne inhalable dust from workplaces (poultry farms, pig stables, grain storage houses, and a laboratory animal facility) were sampled with portable pumps and measured with both the mAb-EIA and Glucatell assay. Using carboxymethylated curdlan as a standard, the mAb-EIA gave a steep dose-response curve for concentrations between 0.36-15 ng/ml. The mAb-EIA was specific for (1-->3)-beta-D-glucan and was sufficiently sensitive to detect (1-->3)-beta-D-glucan in airborne dust samples. In comparing the EIA results to the values obtained with the Glucatell assay, the correlation was found to be high (coefficient of correlation r(2)=0.91), and the mean ratio of the values was 1.7. Depending on the dust source, either the Glucatell assay or the mAb-EIA gave higher results. The mAb-EIA is sensitive enough to detect (1-->3)-beta-D-glucan in airborne dust samples collected with portable pumps. Thus, the assay is suited for the investigation of the health effects induced by exposure to this class of biologically active molecules.

Occupational hypersensitivity pneumonitis due to molds in an onion and potato sorter

A 42-year-old female non-smoking onion and potato sorter developed work-related shortness of breath, cough, fatigue and flu-like symptoms. The diagnosis of hypersensitivity pneumonitis was based on patchy infiltrates in both lungs on high resolution computed tomography and lymphocytosis of 71% in a bronchoalveolar lavage sample with a CD4/CD8 ratio of 0.4. Exposure cessation and initial corticosteroid therapy resulted in complete recovery. IgG antibodies to Penicillium species and Fusarium solani cultivated from samples from the patient's workplace were detected in the patient's serum and cross-reactivity was demonstrated within Penicillium species, but also between Penicillium species and Aspergillus fumigatus. We conclude that occupational hypersensitivity pneumonitis due to molds may develop in onion and potato sorters.

Quantitative analysis of immunoglobulin E reactivity profiles in patients allergic or sensitized to natural rubber latex (Hevea brasiliensis)

BACKGROUND

Characterized native and recombinant Hevea brasiliensis (rHev b) natural rubber latex (NRL) allergens are available to assess patient allergen sensitization profiles.

OBJECTIVE

Quantification of individual IgE responses to the spectrum of documented NRL allergens and evaluation of cross-reactive carbohydrate determinants (CCDs) for more definitive diagnosis.

METHODS

Sera of 104 healthcare workers (HCW; 51 German, 21 Portuguese, 32 American), 31 spina bifida patients (SB; 11 German, 20 Portuguese) and 10 Portuguese with multiple surgeries (MS) were analysed for allergen-specific IgE antibody (sIgE) to NRL, single Hev b allergens and CCDs with ImmunoCAP technology.

RESULTS

In all patient groups rHev b 5-sIgE concentrations were the most pronounced. Hev b 2, 5, 6.01 and 13 were identified as the major allergens in HCW and combined with Hev b 1 and Hev b 3 in SB. In MS Hev b 1 displayed an intermediate relevance. Different sIgE antibody levels to native Hevea brasiliensis (nHev b) 2 and rHev b 6.01 allowed discrimination of SB with clinical relevant latex allergy vs. those with latex sensitization. Sensitization profiles of German, Portuguese and American patients were equivalent. rHev b 5, 6.01 and nHev b 13 combined detected 100% of the latex-allergic HCW and 80.1% of the SB. Only 8.3% of the sera showed sIgE response to CCDs.

CONCLUSIONS

Hev b 1, 2, 5, 6.01 and 13 were identified as the major Hev b allergens and they should be present in standardized latex extracts and in vitro allergosorbents. CCDs are only of minor relevance in patients with clinical relevant latex allergy. Component-resolved diagnostic analyses for latex allergy set the stage for an allergen-directed immunotherapy strategy.

Assessment of soy aeroallergen levels in different work environments

BACKGROUND

Airborne soybean hull proteins are known causes of asthma epidemics around harbours and soy processing plants. Soy flour dust proteins may cause occupational allergy in food and feed industries.

OBJECTIVE

To compare enzyme immunoassays (EIAs) for soy hull and soy flour aeroallergens, exposure assessment in various work environments.

METHODS

Airborne dust samples (n=324) from soy unloading and/or processing plants, the animal feed industry and pig stables were analysed by two soy flour assays: one assay for measuring complete soy hull proteins and two assays for measuring the purified low-molecular-weight (LMW) soy hull allergens.

RESULTS

Immunoblotting confirmed strong differences between antibody specificities and soy preparations. The results of the two soy flour assays and the assay for measuring complete soy hull proteins were highly correlated (r>0.85). The two LMW soy hull assays also showed a strong mutual correlation (r=0.91), but much less correlation with assays for measuring soy flour and complete soy hull. The levels of LMW soy hull proteins were the highest at sites of soybean unloading or processing, while soy flour levels were particularly high in the soy and animal feed industry.

CONCLUSIONS

The optimal EIA procedure for soy aeroallergen exposure assessment depends on the type of work environment and the local soy dust composition. Thus, the type of work environment should always be taken into account in future soy allergy studies in order to prevent a possible underestimation of the workers' actual risk of developing soy allergy.

Optimized methods for fungal ?-amylase airborne exposure assessment in bakeries and mills

BACKGROUND

In order to enable reproducible and comparable exposure measurements of fungal alpha-amylase (alpha-amylase) in different laboratories and countries, the entire procedure from sampling of airborne dust to measuring extracted samples (including standards and the used enzyme) immunoassays must be standardized. The aim of this study was to establish optimal elution and assay conditions.

METHODS

A parallel sampler was used for simultaneous collection of 10 samples of inhalable dust in bakeries and mills in Germany, England, the Netherlands and Spain. Three enzyme-immunoassays (EIAs) for detection of fungal alpha-amylase based on monoclonal antibodies or polyclonal antibodies were used for the measurement of the parallel-sampled filters (n=432) extracted using several methods. The results were analysed by regression analysis of variance. Additional filters (n=54) were extracted and analysed using two EIAs to investigate the storage stability of the extracts.

RESULTS

Although alpha-amylase concentrations correlated well (r> or =0.88), differences were found between the EIAs in the sensitivity and nominal values (up to a mean factor 5.8). The best elution medium for airborne filters (phosphate-buffered saline 'PBS' with 0.05% Tween-20) led to 1.2 to two times higher alpha-amylase allergen yields than extraction in PBS only, while higher Tween-20 concentrations decreased the extracted alpha-amylase yield. During storage of frozen dust/filter extracts for 3-4 months at -20 degrees C, a loss of approximately 40% of measurable alpha-amylase was observed, which could be partially prevented by addition of 0.1% casein to the medium directly after extraction.

CONCLUSION

Although the effects of only a few of many possible causes of variation were investigated, for these factors a clear choice could be made with regard to optimal elution conditions and the use of validated EIAs with calibrated standards, thus making significant progress towards a completely standardized procedure for airborne alpha-amylase measurements.

Airborne exposure to wheat allergens: measurement by human immunoglobulin G4 and rabbit immunoglobulin G immunoassays

BACKGROUND

Exposure to airborne wheat allergens in the bakery trade is associated with a high risk of occupational allergy and asthma. Control and reduction of allergen exposure require relatively simple but reliable monitoring techniques. We developed new rabbit IgG-based enzyme immunoassays (EIA) for wheat allergens, which might be a convenient alternative for the thus far used human IgG4 inhibition assay.

METHODS

The reactivity and specificity of rabbit antibodies were assessed by EIA and immunoblotting, and compared with those of IgE from wheat-sensitized bakers, and with the antibodies used in the IgG4 inhibition EIA. An IgG inhibition and a sandwich EIA were developed for analysis of airborne dust samples.

RESULTS

Human IgG4 and rabbit IgG inhibition EIAs had comparable sensitivities, with limits of detection (LOD) between 18 and 88 ng/mL, while the sandwich EIA was much more sensitive (LOD<0.2 ng/mL). Human IgG4 and rabbit IgG reacted in immunoblotting with most of the IgE-binding wheat proteins, although with quantitative differences. All three assays showed a strong reaction with wheat proteins, and some cross-reactivity with rye and barley, but were further highly specific for cereal flour proteins. Concentrations measured with the three EIAs in 432 airborne dust samples were highly correlated (r>0.95) and their absolute values showed less than 10-20% differences.

CONCLUSION

The rabbit IgG EIAs are valid substitutes for the human IgG4 inhibition EIA, with important practical advantages. The inhibition EIA is recommended for routine wheat allergen measurements. The sandwich EIA may be used to measure low allergen levels, as in short task-related exposure measurements or in subfractions of airborne dust samples.

Occupational immunoglobulin E-mediated asthma due to Penicillium camemberti in a dry-sausage packer

A 62-year-old female sausage packer reported progressive work-related asthma, rhinitis and contact urticaria after contact to dry sausages refined by moulds. Whereas skin prick tests with commercial mould extracts were negative, the patient showed weak skin sensitization to a cultivated mould sample from a dry sausage. Specific immunoglobulin E antibodies to various moulds were demonstrated by ImmunoCAP and antibodies to the cultivated mould sample were demonstrated by enzyme allergosorbent test. The mould was identified by pheno- and genotyping as Penicillium camemberti. Five atopic controls did not show sensitization with the same tests. Crossreactivity of P. camemberti and Penicillium notatum was shown by enzyme allergosorbent inhibition tests. Although no challenge tests were considered due to the patient's airway obstruction, a diagnosis of allergic occupational asthma was made. We conclude that immunoglobulin E-mediated allergic occupational asthma due to moulds may occur in dry sausage packers.

A rapid lateral flow immunoassay for the detection of fungal alpha-amylase at the workplace

Fungal alpha-amylase is a flour supplement which is added to improve the quality of bakery products. Various studies have shown that exposure to this enzyme is an important risk factor for the development of bakers' allergy and this allergy is reported to be one of the most frequent causes of occupational asthma. A rapid assay was developed to monitor exposure to occupational allergens directly at the workplace. The sensitivity of the developed assay is 0.32 ng amylase mL(-1) in a buffer system with the commercially available alpha-amylase preparation Fungamyl 1600S as the standard. Initial validation tests (n = 33) were performed with airborne and settled dust from an industrial bakery. The new lateral flow immunoassay detected amylase in 22 of the 26 samples regarded as positive in an enzyme immunoassay, and was negative for all seven enzyme immunoassay-negative samples, while the four lateral flow immunoassay-negative/enzyme immunoassay-positive samples all had levels below 2 ng mL(-1). The sensitivity of 2 ng mL(-1) of the amylase lateral flow immunoassay is sufficient for first screening purposes and, therefore, this simple and rapid assay may allow direct on-site demonstration of work-related hazards of bio-allergen exposure. This would be particularly useful in occupational hygiene practice, especially in traditional or small-scale bakeries which lack the technological skills for testing the exposure to respiratory allergens.

Sensitization due to gum arabic (Acacia senegal): the cause of occupational allergic asthma or crossreaction to carbohydrates?

BACKGROUND

A pharmaceutical industry worker was exposed to dust of gum arabic in the tablet coating plant and complained of work-related shortness of breath, chest tightness, runny nose, itching and redness of the eyes. This case was investigated for allergy to gum arabic and compared with a control group. The aim of the study was to identify the IgE-binding components responsible for the work-related symptoms.

METHODS

Skin prick tests (SPTs)and specific IgE (sIgE) measurements with environmental and occupational allergens, spirometry and a specific bronchial challenge with gum arabic were performed. One hundred and nineteen control subjects underwent SPT with gum arabic and 43 controls were tested for sIgE. Crossreactivity between gum arabic and horse radish peroxidase was investigated by IgE CAP inhibition. A combined procedure of immunoblotting and periodate treatment was applied to identify the epitope nature of gum arabic.

RESULTS

Allergy to gum arabic was shown by SPT, presence of sIgE and a positive bronchial challenge with gum arabic. Sensitization to gum arabic was demonstrated by SPT or sIgE in 7 and 5 controls, respectively. The results of inhibition with horse radish peroxidase, immunoblotting and periodate treatment suggest that gum arabic sIgE of the patient and 1 SPT-positive control subject were directed to the polypeptide chains of gum arabic. In contrast, gum arabic sIgE of the other controls reacted to carbohydrate components.

CONCLUSIONS

Sensitization to gum arabic carbohydrate structures occurs casually in atopic patients with pollen sensitization without obvious exposure to gum arabic. This study suggests that allergy to gum arabic is mediated preferentially by IgE antibodies directed to polypeptide chains of gum arabic.

Airborne exposure to wheat allergens: optimised elution for airborne dust samples

Well-validated methods for measuring airborne occupational allergens are essential for effective control and reduction of allergen exposures. For wheat flour allergens, specific immunoassays are available, but there is a need for optimisation and standardization of sample processing procedures. Wheat flour allergen elution and storage were studied using airborne dust samples collected in bakeries with a new parallel sampler. Forty-eight series of 9 parallel filters were subjected to extraction procedures varying in elution medium, shaking method, extraction vial, and centrifugation speed. Wheat allergens were measured with enzyme immunoassays, and the effect of various procedures evaluated by mixed regression analyses. The stability of the eluted allergens was assessed after storage for 20 days and 4 months at -20 degrees C, in the presence or absence of casein in the medium. Only the type of elution medium had significant effects on allergen recovery: addition of Tween-20 resulted in 3- to 100-fold increased levels, an effect that was most pronounced at low concentrations. Allergen levels in extracts were stable for at least 4 months at -20 degrees C, irrespective of the presence of casein in the medium. Addition of Tween-20 to the elution medium is essential for optimal extraction of wheat allergen. The recommended procedure further includes the use of conventional polystyrene tubes, simple shaking methods, and centrifugation after extraction. Wheat dust extracts in PBS-Tween can be stored frozen for at least 4 months, and addition of a stabilising protein is not required.

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.

Immunoglobulin E-reactivity of wheat-allergic subjects (baker's asthma, food allergy, wheat-dependent, exercise-induced anaphylaxis) to wheat protein fractions with different solubility and digestibility

Baker's asthma, food allergy to wheat, and wheat-dependent, exercise-induced anaphylaxis (WDEIA) are different clinical forms of wheat allergy. We investigated the correlation of solubility and digestion stability of wheat allergens with the IgE-reactivity patterns of different patient groups. Three wheat protein fractions were extracted according to their solubility: salt-soluble albumins and globulins, ethanol-soluble gliadins, and glutenins soluble only after treatment with detergents and reducing reagents. Sera from subjects with history of each variant of wheat allergy were characterized by CAP FEIA and immunoblotting. There was a high degree of heterogeneity of recognized allergens between the different subject groups as well as within these groups. However, subjects with WDEIA showed similar immunoglobulin E (IgE)-reactivity patterns to gliadins and especially to a 65 kDa protein. Subjects with baker's asthma as well as the food-allergic subjects had the most intense IgE-reactivity to the albumin/globulin fraction. The latter group additionally showed IgE-reactivity to the other fractions. Divergent results of immunoblotting and CAP-FEIA demonstrated that the detection of wheat-specific IgE highly depends on the applied method, thus the diagnostic tool must be carefully chosen. Most wheat allergens were rapidly digested as analyzed by determination of IgE-reactivity on immunoblots to wheat extracts after simulation of gastric and duodenal digestion. However, ethanol-soluble gliadins were stable to gastric enzymes and exhibit low solubility in gastric and duodenal fluids. Therefore, they are likely to be important in food allergy to wheat.

A new method to bind allergens for the measurement of specific IgE antibodies

BACKGROUND

Detection of allergen-specific IgE antibodies in patients' sera plays a key role for the diagnosis of IgE-mediated allergy. If no validated test system is available, diagnostic tools must be developed, usually by coupling or binding the allergens to a solid phase. Streptavidin ImmunoCAP is a new solid phase for binding of allergens which can be used in the Pharmacia CAP system.

OBJECTIVE

It was the aim of this study to assess the diagnostic validity of Streptavidin ImmunoCAP.

METHODS

Biotinylation and allergen concentration for binding to Streptavidin ImmunoCAP were optimized and IgE obtained with natural rubber latex, obeche wood, wheat and rye flour Streptavidin ImmunoCAP were compared with the results of ImmunoCAP and Enzyme Allergo-Sorbent Test (EAST) using sera from patients complaining of workplace-related respiratory symptoms.

RESULTS

While the relation of biotin-label and protein was critical (best results were obtained with a 5- fold molar excess), labelled protein for coupling to streptavidin ImmunoCAP was applicable in a wide concentration range. On average, IgE values with streptavidin ImmunoCAP were as high as with ImmunoCAP but considerably higher than values obtained by EAST.

CONCLUSION

Streptavidin ImmunoCAP is a valuable tool for sensitive and specific measurement of IgE binding to new allergens superior to cellulose disk-based methods.