Exposure levels of animal allergens, endotoxin, and β-(1,3)-glucan on a university campus of veterinary medicine

OBJECTIVES

The study aimed to determine the allergen, endotoxin and β-(1,3)-glucan concentrations at various areas on a university campus of veterinary medicine.

METHODS

Dust samples were collected four times a year for three years using electrostatic dust collectors (EDC) at 25 different locations on a campus of veterinary medicine and in laboratories of inorganic chemistry as a control area representing animal-free environment. Major animal allergens from dog, cat, horse, cattle and mouse, domestic mite (DM) allergens, and β-(1,3)-glucan were measured using enzyme immunoassays and endotoxin using the limulus amoebocyte lysate (LAL) assay. Seasonal, annual and local influences on exposure levels were analyzed using Bayesian mixed models.

RESULTS

With the exception of mouse allergens, all other determinants were found in almost all locations on the campus and in the control area, but in up to 10.000-fold variable concentrations. By far the highest levels of feline, canine, equine and bovine allergens were detected in buildings where the respective species were examined. The highest levels of mouse and DM allergens, β-(1,3)-glucan and endotoxin occurred together and were associated with locations where large animals were present. In buildings without animals, allergen levels were considerably lower but still elevated at several locations compared to the control area, especially for dog and horse allergens, and β-(1,3)-glucan. Significant seasonal effects were observed for dog, cat, horse and DM allergens, and β-(1,3)-glucan. Variations between years were less apparent than between seasons (except for β-(1,3)-glucan).

CONCLUSIONS

The strongest influencing factor on the concentration of mammalian allergens was the presence of the corresponding animal at the collection site. Seasonal influence on allergen concentrations was observed, while the overall exposure remained constant over the years. At locations with horses, elevated levels of mite allergens, endotoxin, and β-(1,3)-glucan can be expected, probably due to passive transfer from stable environment.

Standardisation of allergen products: 4. Validation of a candidate European Pharmacopoeia standard method for quantification of major grass pollen allergen Phl p 5

BACKGROUND

The aim of the BSP090 project is the establishment of European Pharmacopoeia Chemical Reference Substances (CRSs) in combination with corresponding standard ELISA methods for quantification of major allergens in allergen products. Here, we present data of a Phl p 5-specific sandwich ELISA that proved suitable for the quantification of Phl p 5, one of the major Timothy grass (Phleum pratense) pollen allergens.

METHODS

A Phl p 5-specific ELISA system was assessed with respect to accuracy, precision, inter-assay (within laboratory) and inter-laboratory variations, in a ring trial including 14 laboratories in Europe and the USA. Model samples containing recombinant Phl p 5a CRS as well as native grass pollen extracts were analysed. Each participant was instructed to perform at least one preliminary assay to familiarise with the protocol, followed by three independent assays.

RESULTS

The candidate standard ELISA proved suitable to quantify recombinant and native Phl p 5 with satisfactory precision (93% of results within ±30% acceptance range). Inter-assay variation (max. GCV 24%) and especially inter-laboratory variation (max. GCV 13%) showed conclusive results. When assessing accuracy by means of recovery of recombinant spikes from a grass pollen extract matrix, similarly satisfactory spike recovery results were observed for the two spikes with higher concentrations (all within ±30% acceptance range), whereas recovery of the lowest concentration spike was slightly poorer with mean results of six laboratories exceeding acceptance range.

CONCLUSIONS

Based on the collaborative study results, the assessed Phl p 5-specific immunoassay is appropriate to be proposed as European Pharmacopoeia standard method.

Quantitative measurement of IgG to SARS-CoV-2 antigens using monoclonal antibody-based enzyme-linked immunosorbent assays

OBJECTIVE

Standardised quantitative analysis of the humoral immune response to SARS-CoV-2 antigens may be useful for estimating the extent and duration of immunity. The aim was to develop enzyme-linked immunosorbent assays (ELISAs) for the quantification of human IgG antibodies against SARS-CoV-2 antigens.

METHODS

Enzyme-linked immunosorbent assays were developed based on monoclonal antibodies against human IgG and recombinant SARS-CoV-2 antigens (Spike-S1 and Nucleocapsid). The WHO 67/086 immunoglobulin and WHO 20/136 SARS-CoV-2 references were used for standardisation. Sera of a study group of COVID-19-positive subjects (n = 144), pre-pandemic controls (n = 135) and individuals vaccinated with BioNTech-Pfizer BNT162b2 vaccine (n = 48) were analysed. The study group sera were also tested using EuroImmun SARS-CoV-2-ELISAs and a quantitative S1-specific fluorescence enzyme immunoassay (FEIA) from Thermo Fisher.

RESULTS

The ELISA results were repeatable and traceable to international units because of their parallelism to both WHO references. In the study group, median anti-S1-IgG concentrations were 102 BAU mL-1, compared to 100 and 1457 BAU mL-1 in the vaccination group after first and second vaccination, respectively. The ELISAs achieved an area under the curve (AUC) of 0.965 (S1) and 0.955 (Nucleocapsid) in receiver operating characteristic (ROC) analysis, and a specificity of 1 (S1) and 0.963 (Nucleocapsid) and sensitivity of 0.903 (S1) and 0.833 (Nucleocapsid) at the maximum Youden index. In comparison, the commercial assays (S1-FEIA, S1 and Nucleocapsid ELISA EuroImmun) achieved sensitivities of 0.764, 0.875 and 0.882 in the study group, respectively.

CONCLUSIONS

The quantitative ELISAs to measure IgG binding to SARS-CoV-2 antigens have good analytical and clinical performance characteristics and units traceable to international standards.

Comparing the concentration levels of allergens and endotoxins in employees' homes and offices

Objective

The aim of the study was to find out whether allergen and endotoxin concentrations in offices differ from those measured at the homes of employees, and identify the parameters that influence exposure.

Methods

Electrostatic dust collectors (EDCs) were placed in five office buildings (68 rooms, 436 EDCs), as well as the homes of the office workers (145 rooms, 405 EDCs) for 14 days, four times a year. In addition, surface samples were collected from the offices four times a year by vacuuming the carpeted floors. Domestic mite (DM), and the major cat and dog allergens (Fel d 1 and Can f 1) were quantified in all samples using fluorescence enzyme immunoassays. Endotoxin was measured in the EDC samples, using the Limulus amoebocyte lysate assay. The allergen and endotoxin concentrations were log transformed and analysed with multilevel models.

Results

Endotoxin concentrations were significantly higher in personal homes compared to levels measured in the offices, and depended on the number of persons living in each household, as well as the presence of a dog. DM allergens were significantly higher in households than in offices, and were significantly higher in bedrooms compared to living rooms. Offices occupied by cat owners had significantly higher Fel d 1 concentrations than offices or homes without. Additionally, Can f 1 concentrations were significantly higher in offices occupied by dog owners compared to those without.

Conclusions

Pet owners appear to transfer cat and dog allergens to their offices. Therefore, in case of allergy complaints at the office, employers and physicians might consider possible contamination by cat and dog allergens.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-021-01794-9.

Animal Allergens, Endotoxin, and β-(1,3)-Glucan in Small Animal Practices: Exposure Levels at Work and in Homes of Veterinary Staff

OBJECTIVES

In veterinary settings, high exposures to animal allergens and microbial agents can be expected. However, occupational exposure levels are largely unknown. The objective of this study was to estimate the allergen, endotoxin, and β-(1,3)-glucan concentrations in small animal practices and in the homes of practice employees.

METHODS

Dust samples were collected using electrostatic dust fall collectors in diverse rooms of 36 small animal practices, as well as in employees' homes. Major animal allergens (Fel d 1, Can f 1, Ory c 3, Cav p 1, Equ c 1, Bos d 2), domestic mite (DM) allergens, and β-(1,3)-glucan levels were measured using enzyme immunoassays. Endotoxin was determined using the Limulus amoebocyte lysate assay. Influences on exposure levels were analyzed using multilevel models.

RESULTS

The levels of Can f 1, Fel d 1, Ory c 3, and Cav p 1 were up to 30 times higher in practices compared with homes without animals, but significantly lower compared with the homes with the respective pet. Although horses were not treated in the practices, Equ c 1 was found in 87.5% of samples, with the highest concentrations measured in changing rooms. DM levels were significantly lower in practices than in all private homes, and endotoxin levels were similar to those in homes with pets. In the practice itself, exposure levels were significantly influenced by animal presence, type of the room, and area per employee; whereas, room volume and diverse cleaning measures had mostly no effect.

CONCLUSIONS

Exposure to animal allergens is high in veterinary practices, but it does not reach levels of households with pets. Domestic mite allergen and endotoxin exposure seem to be low for workers in veterinary practices. The high Equ c 1 detection rate strongly indicates dispersal of allergens, most likely through clothing and hair.

Reliability and Correlation Between Indoor Allergen Concentrations from Vacuumed Surface Samples and Electrostatic Dust Collectors

OBJECTIVES

Most studies on indoor allergen exposure used vacuumed surface samples for quantification. One alternative is electrostatic dust collectors (EDCs), which sample previously airborne settled dust. The aim of this study was to compare allergen quantification using two different sampling methods, with respect to repeatability, and to determine how well the results agree with one another.

METHODS

Four times a year, measurements were made from samples that were either collected from the vacuuming of surfaces, or from EDCs, from 20 German day-care centers totaling 167 rooms. Overall, 504 vacuumed samples collected from smooth floors, 435 samples from carpets, 291 samples from upholstered furniture and beds, and 605 EDC samples were analyzed using six fluorescence enzyme immunoassays recognizing Fel d 1, Can f 1, Mus m 1, domestic mite (DM), Dermatophagoides pteronyssinus (Dp), and Tyrophagus putrescentiae (Tp) antigens. Variances and correlations among the repeat measurements over the course of the year within each sample type, and the correlations between surface samples and the corresponding EDC samples were calculated.

RESULTS

Repeat measurements over the year correlated significantly with one another. However, only Fel d 1, Can f 1, and DM in the EDC samples; DM, Dp, Tp, and Fel d 1 in the upholstered furniture samples; and DM in the carpet samples show representative results of single measurements according to their variance ratios (within-room/between-room variance <1). The highest correlation between surface and EDC samples was found for Fel d 1 on the upholstered furniture (r 0.52), followed by Can f 1 on the upholstered furniture and Can f 1 on carpets (r 0.47 and 0.45, respectively). The maximum correlation for mite antigens was between carpet samples and EDC (DM r 0.27, Dp r 0.33). Mus m 1 and Tp antigens for the most part did not correlate to the EDC results.

CONCLUSIONS

Both vacuumed dust from upholstered furniture and EDC samples were suitable for repeatable quantification of several allergens in day-care centers within a year. However, there was little agreement among the different collection methods, especially for Mus m 1 and certain mite antigens. Therefore, the method and location used for collection may greatly influence allergen exposure assessment and study results.

Bovine Allergens in a Ruminant Clinic and Dairy Barns: Exposure Levels, Determinants, and Variability

Background

Dairy farmers may develop specific sensitization and allergic airway diseases due to bovine allergens. However, dose-response relationships are lacking, and as yet little is known on bovine allergen exposure levels.

Objective

To investigate bovine allergen exposure levels in a ruminant clinic and dairy barns, and to assess exposure determinants and variability of exposure.

Methods

Samples were collected using active and passive airborne dust measurements in a ruminant clinic and several dairy barns. Bovine allergen levels were determined by sandwich enzyme-linked immunosorbent assay. Linear mixed models were applied to explore the association between bovine allergen exposure levels and potential exposure determinants. Day-to-day within-worker and between-worker exposure variability was determined, as well as how exposure determinants affect exposure variability.

Results

Bovine allergens were measureable in all samples. Personal bovine allergen exposure levels in the ruminant clinic ranged from 0.10 to 24.8 µg/m3, geometric mean (GM) 1.34 µg/m3. Exposure levels varied dependent on job titles. Personal exposure levels in dairy barns ranged from 0.10 to 46.8 µg/m3, GM 1.47 µg/m3. Type of bedding materials in the barns appeared to be a significant determinant of bovine allergen levels. Compost bedding, particularly, increased allergen levels. Milking by robot was the most important determinant explaining between-worker exposure variability, while bedding was important as well. Bovine allergen levels in stationary measurements were somewhat lower than personal measurements (GM ratio 0.47). Bovine allergens could be readily detected in electrostatic dust-fall collector measurements.

Conclusion

This study provides insight in bovine allergen exposure levels and their determinants, which is a first step to investigate dose-response relationships between sensitization/allergy associated with exposure to bovine allergen levels in future studies.

Baker's Asthma: Is the Ratio of Rye Flour-Specific IgE to Total IgE More Suitable to Predict the Outcome of Challenge Test Than Specific IgE Alone

Usually the diagnosis of baker's asthma is based on specific inhalation challenge with flours. To a certain extent the concentration of specific IgE to flour predicts the outcome of challenge test in bakers. The aim of this study was to evaluate whether the ratio of specific IgE (sIgE) to total IgE (tIgE) improves challenge test prediction in comparison to sIgE alone. Ninety-five bakers with work-related respiratory symptoms were challenged with rye flour. Total IgE, sIgE, and the sIgE/tIgE ratio were determined. Receiver operator characteristic (ROC) plots including the area under the curve (AUC) were calculated using the challenge test as gold-standard. Total IgE and sIgE concentrations, and their ratio were significantly higher in bakers with a positive challenge test than in those with a negative one (p < 0.0001, p < 0.0001, and p = 0.023, respectively). In ROC analysis, AUC was 0.83 for sIgE alone, 0.79 for tIgE, and 0.64 for the ratio. At optimal cut-offs, tIgE, sIgE, and the ratio reached a positive predicted value (PPV) of 95%, 84% and 77%, respectively. In conclusion, calculating the ratio of rye flour-sIgE to tIgE failed to improve the challenge test prediction in our study group.

Lower allergen levels in hypoallergenic Curly Horses? A comparison among breeds by measurements of horse allergens in hair and air samples

Background

Exposure to horses can cause severe allergic reactions in sensitized individuals. The breed, American Bashkir Curly Horse is categorized as hypoallergenic, primarily due to reports of allergic patients experiencing fewer symptoms while handling this special breed. The possible reasons for this phenomenon could be lower allergen production and/or reduced allergen release into the air because of increased sebum content in their skin and hair compared to other breeds. Therefore, the aim of the current study was to compare different horse breeds in relation to allergen content in hair and airborne dust samples.

Methods

In total, 224 hair samples from 32 different horse breeds were investigated. Personal nasal filters were used to collect airborne dust during the grooming of 20 Curly Horses and 20 Quarter Horses. Quantitative analysis of all samples was performed using two newly developed immunoassays for the detection of horse dander (HD) antigens and the major allergen Equ c 1 and the commercial assay for Equ c 4. Results were analyzed using multiple linear regression models for hair samples and the Mann Whitney U test for airborne samples.

Results

Horse antigen and allergen levels differed up to four orders of magnitude between individual animals. Despite enormous variability, levels of HD antigen, Equ c 1 and Equ c 4 in hair were significantly related to the breed and gender combined with the castration status of male animals. Curly Horses had significantly higher concentrations of all three tested parameters compared to the majority of the investigated breeds (medians: 11800 μg/g for HD antigen, 2400 μg/g for Equ c 1, and 258 kU/g for Equ c 4). Tinker Horses, Icelandic Horses and Shetland Ponies were associated with approximately 7-fold reduced levels of HD antigen and Equ c 1, and up to 25-fold reduced levels of Equ c 4 compared to Curly Horses. Compared to mares, stallions displayed increased concentrations of HD antigens, Equ c 1 and Equ c 4 by a factor 2.2, 3.5 and 6.7, respectively. No difference was observed between mares and geldings. No differences in airborne allergen concentrations collected with personal nasal filters during grooming were found between Curly and Quarter Horses.

Conclusion

Breed and castration status had a significant influence on the antigen and allergen levels of horse hair. However, these differences were smaller than the wide variability observed among individual horses. Compared to other breeds, Curly Horses were not associated with lower allergen levels in hair and in air samples collected during grooming. Our approach provides no molecular explanation why Curly Horses are considered to be hypoallergenic.

Indoor allergen levels in settled airborne dust are higher in day-care centers than at home

BACKGROUND

Early-life sensitization to indoor allergens predicts asthma development. The aim of this study was to compare allergen concentrations in day-care centers (DCC) with those in private homes.

METHODS

Settled airborne dust was collected 4 times a year from 20 German DCC (620 samples) and from the homes of children and day-care workers (602 samples) using electrostatic dust collectors (EDC). The samples were analyzed with fluorescence enzyme immunoassays recognizing domestic mite allergens (DM), Fel d 1, Can f 1, and Mus m 1. Pet allergen thresholds that discriminate samples from homes with cats or dogs from those without were calculated using receiver-operating characteristics. Influences on allergen levels were analyzed using multilevel models.

RESULTS

Allergen loads were on average higher in DCC than in homes. In DCC, 96% of the samples were positive for DM, 95% for Can f 1, 90% for Fel d 1, and 83% for Mus m 1. In homes, 84% contained DM, 48.5% Can f 1, 33% Fel d 1, and 43% Mus m 1. The threshold level for homes with dogs was 75 ng/m² Can f 1 (96.8% sensitivity, 96% specificity), and the threshold level for homes with cats was 46 ng/m² Fel d 1 (92% sensitivity, 94.9% specificity). In DCC, Can f 1 and Fel d 1 loads were higher than these thresholds in 37% and 54% of the samples, respectively. Allergen levels were significantly influenced by the season and room type; however, carpets on floors had no influence.

CONCLUSIONS

Mite, mouse, cat, and dog allergens were mostly higher in DCC than in homes. Exposure to dog and cat allergens in DCC often reached levels of households with pets.

Occupational generalized urticaria and anaphylaxis after inhalation of cefuroxime in a nurse

We present the case of a 53 years old nonatopic female nurse who experienced repeated anaphylactic reactions at work without involvement in drug-specific tasks such as crushing of tablets or preparation of injections. The causal allergen was not identified until a further severe anaphylactic reaction occurred after oral use of cefuroxime during a respiratory infection. Sensitization to cefuroxime was demonstrated by specific IgE, basophil activation test and skin prick test. An inhalation challenge with a dosimeter induced generalized urticaria after a cumulative dose of about 10 μg of the drug, but no asthmatic reaction. Complete exposure cessation was initiated and a 1-year follow-up was without further allergic reactions. We conclude that work-related systemic allergic reactions to β-lactam antibiotics may occur in nurses after inhalation of low doses and without perceived association with drug-specific tasks like handling of antibiotics.

A recombinant polypeptide of the megakaryocyte potentiating factor is a potential biomarker in plasma for the detection of mesothelioma

Malignant mesothelioma (MM) is a fatal disease mostly associated with asbestos exposure and difficult to detect by non-invasive methods. This study aimed to use recombinant fragments of the megakaryocyte potentiating factor (MPF) for the development of cost-effective MPF ELISAs. Three polypeptides spanning the MPF region (MPF_1-148, MPF _34-288, MPF/MSLN_254-400) were produced in E.coli as maltose-binding protein hybrids. After isolation, Factor Xa digest, and purification, the polypeptides were used for the generation of rabbit antibodies and development of ELISAs. Forty-one MM patients with known histological subtype before tumor-specific treatment and 70 asbestos-exposed individuals free of any cancer were matched according to age, gender, and smoking. Plasma of all subjects was tested with the three newly developed polyclonal antibody-based ELISAs and a commercial mesothelin assay (MESOMARK™). The latter differentiated patients (median concentration 1.95 nM) from controls (median 1.07 nM, p < 0.0001) and showed an area under curve (AUC) of 0.77 in receiver operating characteristics (ROC) analysis. Of the MPF variants, exclusively the ELISA based on antibodies against the MPF_34-288 fragment displayed significantly (p = 0.0002) higher values in patients than in controls (median 1.61 nM versus 0.88 nM; AUC = 0.72). The combination of the MPF_34-288 and mesothelin displayed an improved ROC performance (AUC = 0.80). The MPF_34-288 ELISA could be a cost-effective and minimal-invasive contribution to support a diagnosis of mesothelioma, especially in regions with a limited medical care.

Validation of ELISA methods for quantification of the major birch allergen Bet v 1 (BSP090)

To date, the potency of allergen products in Europe is expressed in manufacturer-specific units relative to a product-specific in-house reference. Consequently, cross-product comparability of allergen products from different manufacturers with respect to strength and efficacy is impossible. The Biological Standardisation Programme (BSP) project BSP090 addresses this issue via the establishment of reference standards in conjunction with ELISA methods for the quantification of major allergens in allergen products. Since the initiation of BSP090, the recombinant major allergen Bet v 1 has been adopted by the European Pharmacopoeia Commission as a Chemical Reference Substance (CRS). In parallel, two sandwich ELISA systems for quantification of Bet v 1 were found suitable in preliminary phases of BSP090 to be validated in a large collaborative study. In this study, the candidate ELISA systems were compared with respect to accuracy, precision and variability. Thirteen participating laboratories tested model samples containing the CRS as well as spiked and unspiked birch pollen extracts. Both in pre-testing and in the collaborative study, the 2 candidate ELISA systems confirmed their suitability to quantify recombinant and native Bet v 1. As no clear-cut decision for one of the ELISA systems could be made based on the results of the collaborative study, a post-study testing was performed. Bet v 1 content of 30 birch pollen allergen products was determined in parallel in both ELISA systems. Consequently, 1 candidate ELISA system was selected to be proposed as the future European Pharmacopoeia standard method for Bet v 1 quantification.

Medical surveillance and long-term prognosis of occupational allergy due to platinum salts

PURPOSE

Medical surveillance of workers in precious metals refineries and catalyst production plants is well established in many countries as a measure to prevent occupational asthma due to platinum (Pt) salts. It was the aim of this study to evaluate the impact of medical surveillance and to define prognostic factors with an emphasis on exposure determinants.

METHODS

As part of an observational longitudinal study, 96 workers from German precious metals refineries and catalyst production plants with Pt salt allergy underwent a second examination several years (median 67 months) after the initial diagnosis was made.

RESULTS

When the second examination was conducted, 92 subjects (96 %) had already been transferred to jobs with very low or no exposure to Pt salts. The number of subjects with sensitization to Pt salt as assessed by skin prick test (SPT_Pt) decreased from 86 to 52 %, and there was a clear improvement for rhinitis, conjunctivitis and contact urticaria between both examinations. Although the number of subjects with asthma symptoms decreased significantly, at the second examination 74 subjects (77 %) continued to suffer from asthma and 51 subjects (53 %) received asthma medication. Airway obstruction or bronchial hyperresponsiveness persisted in 83 subjects (86 %).

CONCLUSIONS

Secondary prevention in subjects with occupational exposure to Pt salts, as practiced for over 25 years in Germany could not avoid persistent asthma in the majority of cases, although improvements occurred. This study reveals the limitations of the concept that removal from exposure after the occurrence of respiratory symptoms may prevent chronic asthma. It is recommended that removal from exposure should be done immediately after the occurrence of a positive SPT_Pt, irrespective of symptoms.

Standardization of allergen products: 3. Validation of candidate European Pharmacopoeia standard methods for quantification of major birch allergen Bet v 1

BACKGROUND

The BSP090 project aims at establishing European Pharmacopoeia Reference Substances in combination with the corresponding ELISA methods for the quantification of major allergens in allergen products. Two sandwich ELISAs proved suitable for quantification of Bet v 1, the major birch pollen allergen, in preceding phases of BSP090.

METHODS

Two Bet v 1-specific ELISA systems were compared with respect to accuracy and precision in a ring trial including 13 laboratories. Model samples containing recombinant rBet v 1.0101 as well as native birch pollen extracts were measured independently at least three times in each facility. The assessment was completed with a comparative quantification of Bet v 1 in 30 marketed birch allergen products in one laboratory, simulating the future use as reference method.

RESULTS

In the collaborative study, both candidate ELISAs confirmed their suitability to quantify recombinant and native Bet v 1. ELISA-A showed higher precision and lower interlaboratory variability, yet ELISA-B exhibited slightly higher accuracy. Subsequent parallel measurement of Bet v 1 in a panel of 'real-life' birch allergen products indicated better repeatability of ELISA-B. Both systems detected substantial differences in Bet v 1 content between allergen products, but the effect was more pronounced using ELISA-B due to persistently higher values compared to ELISA-A.

CONCLUSIONS

In the collaborative study, no deciding differences were observed between the two candidate ELISAs. Further comparison under conditions simulating the intended use combined with the criterion of long-term availability enabled the selection of one Bet v 1-specific ELISA for proposal as European Pharmacopoeia standard method.

Triticale allergy in a farmer

We present the case of a 29-year-old farmer with hay fever and atopic dermatitis since adolescence who had developed work-related asthma about 5 years earlier. He was sensitized to grass pollen, wheat and rye flour, dust from the floors of the animal facilities (cows and pigs) and grain barn, and a battery of animal feed from his farm. Work-relatedness of his asthma was demonstrated by serial measurements of spirometry and fractional exhaled nitric oxide at work and during a holiday. Immunoblot analyses revealed dominant IgE-binding to grass pollen and triticale (a hybrid of rye and wheat). IgE inhibition experiments demonstrated that sensitization to triticale was not due to cross-reactivity to grass pollen. Testing of specific IgE-antibodies to recombinant wheat allergens showed sensitizations to profilin, peroxidase, and nonspecific lipid transfer proteins type I subfamily 9.1 and 9.7. We conclude that triticale allergy may occur as a distinct allergy in farmers. Am. J. Ind. Med. 59:501-505, 2016. © 2016 Wiley Periodicals, Inc.

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.

Allergen quantification in surface dust samples from German day care centers

Indoor allergens are among the main causes of allergic rhinitis and asthma. Allergen exposure is not limited to private homes. Mite, cat, and dog allergens were measured in day care centers to determine whether these concentrations detected might exert significant influence on human health. In 20 day care centers across North Rhine-Westphalia, Germany, the surfaces of 171 rooms were vacuumed 4 times a year to collect dust (1340 samples in total). In all samples, domestic mite antigens (DM) and the main allergens of cats (Fel d 1) and dogs (Can f 1) were quantified using enzyme immunoassays. Provisional threshold limits (PTL) for increased risks of sensitization and allergic symptoms were estimated according to published values and conversion factors. The influence of room characteristics on allergen concentrations was analyzed in mixed linear models, also considering values below the limit of detection (LOD). Nearly all samples contained allergens (99% DM, 96% Fel d 1, and 96% Can f 1). The concentrations rarely exceeded levels that were previously found to induce symptoms in home environments, but were frequently higher than estimates for enhanced sensitization risk (13% DM, 43% Fel d 1, and 27% Can f 1). Upholstered furnishings had the highest dust and allergen loads, followed by carpets and smooth floors. Allergen concentrations on different surface types that were sampled in the same room at the same time were significantly correlated and analyzed in separate models. The highest DM concentrations were present in bedrooms and in autumn. Further, DM loads on floors decreased significantly in rooms that were renovated within the last 5 years. If there were no records that furnishings were vacuumed, there were then significantly higher Can f 1 loads. Sweeping floors elevated DM and cat allergen concentrations. In addition to mite allergens, cat and dog allergens were detected in nearly all samples from day care centers. Overall, the present results indicate that allergen concentrations may be reduced by renovation and appropriate cleaning procedures.

Serial measurements of exhaled nitric oxide at work and at home: a new tool for the diagnosis of occupational asthma

Whereas serial measurements of lung function at work and at home are a well-known diagnostic tool for the diagnosis of occupational asthma (OA), little is known about the serial measurements of non-invasive parameters such as exhaled nitric oxide (eNO). A 51-year-old baker with variable shortness of breath without relation to work was examined for suspected OA. Skin prick test showed weak sensitizations to wheat and rye flour (without sensitizations to environmental allergens) that were corroborated by in vitro testing (CAP class 3). Baseline FEV1 of 58% predicted and a decrease of forced expiratory volume in 1 s (FEV1) after placebo (sugar powder) of 17% did not allow inhalational challenge testing. The patient performed daily measurements of FEV1 and eNO for about a month during a holiday at home and at work. Whereas symptoms and FEV1 did not show differences between holidays and work periods, eNO showed a clear increase from below 10 ppb to a maximum of 75 ppb. A diagnosis of baker's asthma was made, and the patient quit his job immediately after medical advice. A year afterwards, the patient was still taking asthma medication, but his symptoms had improved, FEV1 had increased to 73% predicted, and eNO was 25 ppb. We conclude that serial measurements of eNO at home and at work may be a useful tool for the diagnosis of OA.

Eosinophilic airway disease in a patient with a negative skin prick test, but a positive patch test with platinum salts--implications for medical surveillance

We present the case of a 52-year-old woman with a topic dermatitis since adolescence who developed work-related hand eczema, cough and runny nose 12 years after she had started working as a laboratory technician at a precious metals refinery. While skin prick test with sodium hexachloroplatinate (SPTPt ) was negative, patch testing with ammonium tetrachloroplatinate was positive after 24, 48, 72, and 96 hr. Inhalation challenge with sodium hexachloroplatinate yielded cough, mild shortness of breath, and a maximal decrease of FEV1 of 8% from baseline 24 hr after the challenge. Significant increases of bronchial hyperresponsiveness, exhaled nitric monoxide and sputum eosinophils were documented after the challenge. We conclude that eosinophilic airway disease due to platinum salts may occur in SPTPt negative subjects. Both, patch testing and inhalation challenge with platinum salts should be considered in SPT negative subjects with occupational exposure to precious metal salts and work-related allergic symptoms.

Allergen Levels in the Hair of Different Cattle Breeds

BACKGROUND

Cattle are well-known sources of respiratory allergens in agricultural environments. Breed-specific differences in Bos d 2 (a major bovine allergen) levels in cattle hair have been previously suggested but not fully characterized. Therefore, the aim of the current study was to determine whether hair from common cattle breeds differs in protein and allergen content.

METHODS

In total, 80 hair samples from 16 different cattle breeds were analyzed. The protein concentration was determined using the Bradford assay. The allergen content was measured using a sandwich ELISA based on polyclonal antibodies against a bovine hair protein extract and a commercial immunoassay based on monoclonal antibodies against Bos d 2. Results are given in micrograms per gram of hair. Statistical analysis was performed using the Kruskal-Wallis test and Spearman's rank correlation.

RESULTS

A wide variability in all 3 tested parameters was observed between the individual samples. The protein content differed by about 35-fold (0.3-12 mg/g), the bovine hair allergen content differed by about 500-fold (37-18,553 µg/g), and the Bos d 2 content differed by about 1,200-fold (5-6,323 µg/g). Protein, bovine hair allergen, and Bod d 2 values correlated strongly and significantly with one another. The median Bos d 2/bovine hair allergen ratio was 0.28. No significant differences were found between the most common breeds in Germany (Simmental, Holstein, and Braunvieh) and a group of rare breeds or between female and male animals.

CONCLUSIONS

The results confirm a high variability in allergen levels between individual animals but also indicate that allergen production is related neither to the breed nor to gender.

[Cockroaches and co. The role of health pests as allergen source]

In most of the cases health pests are carriers of pathogens or parasites which have a negative impact on human health or affect the health of other mammals. What is lesser known is that they can also act as allergens. Most of the health pests in this sense belong to the arthropods, such as cockroaches (Blattaria), mosquitos (Culiciformia), lice (Pediculus humanus corporis), fleas (Siphonaptera) and ticks (Argasidae). In the group of vertebrates rats (Rattus norvegicus and Rattus rattus), house mice (Mus musculus) and pigeons (Columba livia domestica) are also classified as health pests. Also storage pests which are not carriers of pathogens can induce secondary infestation with hygiene pests or molds and have an underestimated impact on human health. In this article selected examples of health pests and also storage pests as an allergen source are described, taking into account the sensitization prevalence and identified single allergens.

IgE sensitization to lupine in bakers - cross-reactivity or co-sensitization to wheat flour?

BACKGROUND

Food allergy to lupine has frequently been reported in patients allergic to peanut or soy, and cross-reactivity between these legumes is known. Moreover, respiratory allergy to lupine has been described after inhalation, mostly at workplaces. Our aim was to study the frequency of lupine sensitization in European bakers with suspected bakers' allergy. Furthermore, associations between sensitizations to lupine and other plant allergens were investigated.

METHODS

One hundred and sixteen bakers with work-related allergic symptoms but without known food allergies were examined. Specific IgE (sIgE) antibodies to wheat flour, rye flour, lupine, peanut, soy and the recombinant single birch protein rBet v 1 were quantified. Selected sera were tested for cross-reactivity using ImmunoCAP inhibition and ISAC microarrays.

RESULTS

Whereas 67% of bakers were sensitized to wheat and/or rye flour, 35% showed sIgE to peanut and 33% to lupine. All lupine-positive bakers also had sIgE to either wheat flour (89%) and/or peanut (92%), and lupine sIgE correlated significantly with sIgE to peanut, soy, wheat and rye flour. Used as an inhibitor, wheat flour inhibited IgE binding to lupine in 4 out of 8 sera, indicating cross-reactivity. In microarrays, these sera showed IgE binding to lipid transfer proteins, profilins and/or cross-reactive carbohydrate determinants. Further inhibition experiments suggest that these single allergens are involved in cross-reactivity.

CONCLUSION

One third of 116 symptomatic bakers showed sIgE to lupine. At least some of these sensitizations were based on cross-reactivity between lupine and wheat flour. However, the considerable sensitization rate could also be a sign that the use of lupine flour in bakeries may be of occupational relevance.

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.

Influence of 5 different caging types and the use of cage-changing stations on mouse allergen exposure

Animal allergens constitute a serious health risk in laboratory animal facilities. To assess possibilities for allergen reduction by technical and organizational measures, we studied personnel exposure to mouse urinary aeroallergens in an animal facility with a holding capacity of 30,000 cages. Short-term (2 h) and intermediate-term (12 h) stationary samples (n = 107) and short-term (2 h) personnel samples (n = 119) were collected on polytetrafluorethylene filters by using air pumps. Long-term (14 d) stationary dust samples containing airborne allergens (n = 165) were collected with electrostatic dust fall collectors (EDC). Mouse allergens were quantified by ELISA. Personnel samples were collected during bedding disposal and refilling of clean cages as well as during cage changing with and without use of cage-changing station. Animal rooms were equipped with either open cages, cages with a soft filter top, cages with a rigid filter top (static microisolation caging), or with individually ventilated cages (IVC) with either a sealed or nonsealed lid, each in positive- or negative-pressure mode. Highest personnel allergen exposure was detected during cage change and emptying of soiled cages. Allergen concentrations were lowest in rooms with sealed IVC under positive or negative pressure, with unsealed IVC under negative pressure, and with static microisolation caging. The use of cage-changing stations and a vacuum bedding-disposal system reduced median personnel exposures 14- to 25-fold, respectively. Using sealed IVC and changing stations minimized allergen exposure, indicating that state-of-the-art equipment reduces exposure to mouse allergens and decreases health risks among animal facility personnel.

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.

Effectiveness of interventions to reduce flour dust exposures in supermarket bakeries in South Africa

RATIONALE

A recent study of supermarket bakery workers in South Africa demonstrated that 25% of workers were sensitised to flour allergens and 13% had baker's asthma. Evidence on exposure reduction strategies using specifically designed interventions aimed at reducing the risk of baker's asthma is scarce.

OBJECTIVES

The aim of this study was to evaluate the effectiveness of different control measures to reduce airborne flour dust exposure using a randomised design.

METHODS

A group-randomised study design was used to assign 30 bakeries of a large supermarket chain store to two intervention groups and a control group, of which 15 bakeries were studied. Full-shift environmental personal samples were used to characterise exposure to flour dust and wheat and rye allergens levels pre-intervention (n=176) and post-intervention (n=208).

RESULTS

The overall intervention effect revealed a 50% decrease in mean flour dust, wheat and rye allergen exposure. The reduction in exposure was highest for managers (67%) and bakers (47%), and lowest for counterhands (23%). For bakers, the greatest reduction in flour dust was associated with control measures such as the use of the mixer lid (67%), divider oil (63%) or focused training (54%). However, the greatest reduction (80%) was observed when using a combination of all control measures.

CONCLUSIONS

A specially designed intervention strategy reduced both flour dust and allergen levels. Best results were observed when combining both engineering controls and training. Further studies will investigate the long-term health impact of these interventions on reducing the disease burden among this group of bakers.

Concentration of bioaerosols in composting plants using different quantification methods

BACKGROUND

Bioaerosols (organic dusts) containing viable and non-viable microorganisms and their metabolic products can lead to adverse health effects in exposed workers. Standard quantification methods of airborne microorganisms are mainly based on cultivation, which often underestimates the microbial burden. The aim of the study was to determine the microbial load in German composting plants with different, mainly cultivation-independent, methods. Second purpose was to evaluate which working areas are associated with higher or lower bioaerosol concentrations.

METHODS

A total of 124 inhalable dust samples were collected at different workplaces in 31 composting plants. Besides the determination of inhalable dust, particles, and total cell numbers, antigen quantification for moulds (Aspergillus fumigatus, Aspergillus versicolor, Penicillium chrysogenum, and Cladosporium spp.) and mites was performed. Concentrations of β-glucans as well as endotoxin and pyrogenic activities were also measured. The number of colony forming units (cfu) was determined by cultivation of moulds and actinomycetes in 36 additional dust samples.

RESULTS

With the exception of particle numbers, concentrations of all determined parameters showed significant correlations (P < 0.0001; r Spearman: 0.40-0.80), indicating a close association between these exposure markers. Colony numbers of mesophilic moulds and actinomycetes correlated also significantly with data of cultivation-independent methods. Exposure levels showed generally large variations. However, all parameters were measured highest in dusty working areas like next to the shredder and during processing with the exception of Cladosporium antigens that were found in the highest concentrations in the delivery area. The lowest concentrations of dust, particles, antigens, and pyrogenic activity were determined in wheel loader cabins (WLCs), which were equipped with an air filtration system.

CONCLUSION

It was possible to assess the microbial load of air in composting plants with different quantification methods. Since allergic and toxic reactions may be also caused by nonliving microorganisms, cultivation-independent methods may provide additional information about bioaerosol composition. In general, air filtration reduced the bioaerosol exposure shown in WLCs. Due to the fact that the mechanical processing of compost material, e.g. by shredding or sieving is associated with the generation of high bioaerosol concentrations, there is still a need of improved risk assessment and state-of-the-art protective measures in composting plants.

Allergens and β-glucans in dutch homes and schools: characterizing airborne levels

Background

Indoor air quality has an effect on respiratory health. Children are more vulnerable to a decreased indoor air quality as their lungs are still developing. We measured levels of allergens and β-(1,3)-glucans in 19 school buildings and determined whether measured levels could be reproduced. School levels were compared to those in 169 homes and the effect of building characteristics on both home and school exposure was explored.

Methods

Electrostatic Dust fall Collectors were placed in school buildings for 8 weeks and in homes for 2 weeks to collect settled airborne dust. Cat, dog, and mouse allergen levels, domestic mite antigen levels and β-(1,3)-glucans were measured in the extracts from the collectors. Results were corrected for sampling duration. Using questionnaire data, relations between measured levels and building and classroom characteristics were explored.

Results

In schools, exposure levels were highest in classrooms and were influenced by the socioeconomic status of the children, the season measurements were performed, moisture status of the building and pet ownership. Repeated measurements in different seasons and over the years showed significantly different levels. Home exposure was influenced by socioeconomic status, occupancy and pet ownership. Domestic mite antigen was found in higher levels in extracts from homes compared to schools while pet allergen levels were 13 times higher in schools compared to homes without pets. For mouse allergen overall levels of exposure were low but still two times higher in schools compared to homes. Levels of β-(1,3)-glucans were also approximately two times higher in schools than in homes.

Conclusion

Exposure levels of several allergens and β-(1,3)-glucans in schools differ over time and are higher than in homes. For children, exposure levels measured at school could contribute to their total exposure as especially animal allergen levels can be much higher in schools compared to homes.

A new immunoassay to quantify fungal antigens from the indoor mould Aspergillus versicolor

Aspergillus versicolor is among the most commonly found moulds in moisture-damaged buildings and can be associated with adverse health effects in humans. This paper reports the development, validation and application of an enzyme immunoassay to quantify A. versicolor antigens. A sandwich ELISA was developed using polyclonal antibodies that recognize a broad range of A. versicolor proteins present in fungal spores and in mycelia fragments. To validate the new method, A. versicolor antigens were quantified in samples collected from homes with visible mould growth, including dust from vacuumed walls and bulk samples of building materials. Antigen concentrations were compared to the results of a commercial ELISA based on monoclonal antibodies (AveX ELISA, Indoor Biotechnologies, Charlottesville, USA) and correlated with colony forming units (CFU) of A. versicolor. The A. versicolor ELISA was very sensitive with a lower detection limit of 120 pg ml(-1). The assay also showed some reactivity to other moulds with strongest reactions with other Aspergillus species (1-3% reactivity). The new assay detected A. versicolor antigens in a much higher percentage of dust samples (88% vs. 27%) and bulk samples (89% vs. 24%) than the AveX assay. A significant correlation (r = 0.67, and p < 0.0001) was found between antigen concentrations and CFU of A. versicolor. Based on its low detection limit and good correlation with the culture-based method, this new immunoassay seems to be a useful tool for the measurement of A. versicolor exposure levels and a reliable complement to the traditional monitoring techniques, such as mould cultivation or microscopy.

Evaluation of commercial skin prick test solutions for selected occupational allergens

BACKGROUND

Skin prick testing (SPT) is an important step in the diagnosis of IgE-mediated occupational allergic diseases. The outcome of SPT is related to the quality of allergen extracts. Thus, the aim of the study was to assess different commercially available SPT solutions for selected occupational allergens.

METHODS

SPT was performed in 116 bakers, 47 farmers and 33 subjects exposed to natural rubber latex (NRL), all with work-related allergic symptoms. The SPT solutions from different manufacturers (n = 3-5) for wheat flour, rye flour, soy, cow hair/dander, storage mites (Tyrophagus putrescentiae, Lepidoglyphus destructor, Acarus siro) and NRL were analysed with respect to their protein and antigen contents. SPT was carried out in 16 allergy centres in six European countries using standardized procedures. Specific IgE values were used as the gold standard to calculate the sensitivity and specificity of SPT solutions. The optimal cut-point for each SPT solution was determined by Youden Index.

RESULTS

Protein and antigen contents and patterns of the SPT solutions varied remarkably depending on the manufacturer. While SPT solutions for wheat flour and soy reached overall low sensitivities, sensitivities of other tested SPT solutions depended on the manufacturer. As a rule, solutions with higher protein and antigen content showed higher sensitivities and test efficiencies.

CONCLUSIONS

There is a wide variability of SPT solutions for occupational allergens, and the sensitivity of several solutions is low. Thus, improvement and standardization of SPT solutions for occupational allergens is essential.

Measurement of β-(1,3)-glucan in household dust samples using Limulus amebocyte assay and enzyme immunoassays: an inter-laboratory comparison

Environmental levels of β-(1,3)-glucan, an inflammatory fungal cell wall component, have been suggested to be related to respiratory symptoms. However there is currently little data comparing β-(1,3)-glucan detection methods and/or results obtained in different laboratories. The aim of this study was to compare levels of β-(1,3)-glucans detected in household dust samples (n = 40) using different extraction/detection methods (Limulus amebocyte assay (LAL), inhibition enzyme immunoassay (EIA) and sandwich EIA) in five different laboratories. Dust sample aliquots were sent to participating centres, extracted and analysed for β-(1,3)-glucan according to standard in-house procedures. Significant differences in the levels of β-(1,3)-glucan were observed between all laboratories (geometric mean levels ranging from 15.4 μg g (-1) to 4754 μg g(-1) dust; p < 0.0001) with the exception of those using a similar LAL method. The inhibition EIA used in laboratory D produced mean β-(1,3)-glucan measurements 80-100 times higher than the LAL assays, 4 times higher than the sandwich EIA in the same lab, 17.6 times those obtained with the EIA in lab E and 363 times those obtained in the EIA in laboratory C. Pearson's correlations generally showed significant associations between methods and laboratories, particularly those using similar methodology (R ranging from 0.5 to 0.8; p < 0.001), although some poor and even inverse correlations were observed. Bland-Altman analyses showed moderate to good agreement between most assays, although clear absolute differences were observed. In conclusion, although results obtained with different methods were often significantly correlated and therefore comparable in relative terms, direct comparison of results between laboratories and assays may be inappropriate.

Domestic mite antigens in floor and airborne dust at workplaces in comparison to living areas: a new immunoassay to assess personal airborne allergen exposure

Objectives

Allergens produced by domestic mites (DM) are among the most common allergic sensitizers and risk factors for asthma. To compare exposure levels between workplaces and living areas a new assay able to measure airborne DM antigen concentrations was developed.

Methods

At workplaces and in living areas, 213 floor dust samples and 92 personal inhalable dust samples were collected. For sensitive quantification of DM antigens, a new enzyme immunoassay (EIA) based on polyclonal antibodies to Dermatophagoides farinae extract was developed. Reactivity of five house dust mite and four storage mite species was tested. All dust samples were tested with the new EIA and with the Der f 1 and Der p 1-EIAs (Indoor Biotechnologies, UK) which detect major allergens from D. farinae and D. pteronyssinus by monoclonal antibodies. Samples below the detection limit in the DM-EIA were retested in an assay variant with a fluorogenic substrate (DM-FEIA).

Results

The newly developed DM-EIA detects antigens from all nine tested domestic mite species. It has a lower detection limit of 200 pg/ml of D.farinae protein, compared to 50 pg/ml for the DM-FEIA. DM antigens were detected by DM-EIA/FEIA in all floor dust and 80 (87%) of airborne samples. Der f 1 was found in 133 (62%) floor dust and in only 6 airborne samples, Der p 1 was found in 70 (33%) of floor samples and in one airborne sample. Der f 1 and DM concentrations were highly correlated. DM-antigens were significantly higher in inhalable airborne samples from textile recycling, bed feather filling, feed production, grain storage and cattle stables in comparison to living areas.

Conclusions

A new sensitive EIA directed at DM antigens was developed. DM antigen quantities were well correlated to Der f 1 values and were measurable in the majority (87%) of airborne dust samples. Some workplaces had significantly higher DM antigen concentrations than living areas.