Animal exposure, sensitization, and allergic symptoms in first-year veterinary medicine students.

The AllergoVet study longitudinally examines the influence of animal exposure on the development of sensitization and allergic diseases among veterinary medicine students. In this group, contact to animals usually existed long before the study began. Therefore, the aim of this analysis was to investigate lifelong animal species-specific exposure and the prevalence of sensitizations and allergic symptoms already existing before the start of the study. Questionnaire data, including exposure history, were summarized to determine the duration and intensity of animal-related exposure as well as the prevalence of allergic symptoms to animals. Serologically, specific IgE was determined against ubiquitous inhalant allergens (atopy screen sx1) and against animal allergens using ImmunoCAP. The association between animal-specific sensitization, allergic symptoms, and exposure was analyzed using Fisher's exact test or Cochran-Armitage trend test. All study participants (n = 313) had previous contact with animals, with dogs mentioned most frequently (91.1%) followed by cats (89.5%) and horses (72.2%). Sensitization to ubiquitous allergens (positive sx1 value) was detected in 38.4% of subjects. Approximately 11%, 7%, and 5% were sensitized to cats, dogs, and horses, respectively. Only a small proportion of these sensitizations were associated with self-reported symptoms (41% for cat, 9% for dog, and 13% for horse). While no significant association between animal-specific exposure and sensitization was found for cats and horses, a clear trend emerged for dogs. With increasing duration of exposure to dogs, the number of dog-specific sensitizations decreased significantly (p = 0.0069). Furthermore, a decreasing trend in sx1 sensitization was noted with increasing cat (p = 0.0288) and dog (p = 0.0107) exposure. None of the subjects who grew up on a farm (n = 40) had any sensitization to animals. The sensitization prevalence determined among first-year students in veterinary medicine roughly corresponds to that in the general population. Most animal sensitizations were not clinically relevant. In this collective, a protective effect of increasing exposure to animals in childhood and adolescence was found on sensitization, which was particularly pronounced during contact with dogs.

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

OBJECTIVES: The study aimed to determine the allergen, endotoxin and ß-(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 ß-(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, ß-(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 ß-(1,3)-glucan. Significant seasonal effects were observed for dog, cat, horse and DM allergens, and ß-(1,3)-glucan. Variations between years were less apparent than between seasons (except for ß-(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 ß-(1,3)-glucan can be expected, probably due to passive transfer from stable environment.

Skin symptoms in veterinary assistant staff and veterinarians: A cross-sectional study.

BACKGROUND: Veterinary assistants and veterinarians are at an increased risk of developing an occupational skin disease, for example, irritant/allergic contact dermatitis, contact urticaria and hand eczema (HE). OBJECTIVES: We aimed to investigate the prevalence of skin problems and the influence of predisposing factors especially among veterinary assistants. METHODS: We conducted a cross-sectional study among veterinary assistant staff (n = 103) and veterinarians (n = 19). A questionnaire, specific IgE determination and photographs of hands were evaluated for skin symptoms. Logistic regression models assessed predisposing factors. RESULTS: Over 50% (n = 62/122) of our study population reported hand eczema (HE) in the last 12 months (1-year prevalence). Twenty-seven subjects reported redness and contact urticaria directly after animal contact, 35 had a positive history of allergic contact dermatitis. HE was associated with (i) increased frequency of hand washing (11-15 times per day; OR 4.15, confidence interval [CI] 95% 1.18-14.6, p = 0.027, univariate model) and (ii) unprotected contact to fluids and tensides >5 times per day (OR 4.56, CI 95% 1.53-13.6, multivariate model). CONCLUSIONS: We observed a high prevalence of self-reported HE among staff in veterinary practices. Excessive hand washing, unprotected contact with irritants and long-term glove use should be avoided.

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.

Animal Allergens, Endotoxin, and ß-(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 ß-(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 ß-(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.

Development of Mold Antigen-Specific Enzyme-Linked Immunosorbent Assays (ELISA) to Quantify Airborne Antigen Exposure.

Common methods to quantify molds in the environment are based on the detection of viable and nonviable fungal components using cultivation technique or assessment by microscopy. These methods are time consuming and laborious and require a high expertise and especially in airborne exposure studies they showed poor reproducibility. Therefore alternative techniques based on molecular or immunological tools attract wide interest. The development of specific ELISAs based on polyclonal antibodies to detect mold antigens in airborne samples starting with the extraction of the antigen material up to evaluation of the sandwich ELISA is summarized in this chapter.

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.

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.

Respiratory Allergens from Furred Mammals: Environmental and Occupational Exposure.

Furry mammals kept as pets, farm and laboratory animals are important allergen sources. The prevalence of sensitization to furred mammals appears to be increasing worldwide. Several mammalian allergens from diverse species are well characterized with regard to their molecular structure and immunogenicity, and some are already available for component-resolved allergy diagnostics. The distribution of various mammalian allergens has been extensively studied during the past few decades. Animal allergens were found to be ubiquitous in the human environment, even in places where no animals reside, with concentrations differing considerably between locations and geographical regions. This review presents an overview of identified mammalian respiratory allergens classified according to protein families, and compiles the results of allergen exposure assessment studies conducted in different public and occupational environments.

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.

Allergen Quantification by Use of Electrostatic Dust Collectors (EDCs): Influence of Deployment Time, Extraction Buffer, and Storage Conditions on the Results.

Sampling of endotoxin, beta-glucan, or allergens on electrostatic dust collectors (EDCs) is a convenient method for exposure assessment. However, especially for allergens few experiments on validation of this method concerning deployment time or storage and extraction procedure have been performed. The aim of study was to optimize the EDC procedure for sampling of allergens in indoor environments. EDCs were placed in households or day-care centers and after extraction, allergens were quantified by six immunoassays detecting mite antigens (Domestic mites DM, Dermatophagoides pteronyssinus Dp, Tyrophagus putrescentiae Tp) or the main allergens from cat (Fel d 1), dog (Can f 1) and mouse (Mus m 1). For 20 EDC holders, deployment times of cloths were varied between 7 and 28 days, 36 EDCs were used to test reproducibility, and for 28 EDCs extraction buffers were varied (with or without 0.05% Tween 20, borate, or phosphate buffer). The influence of storage of cloths at room temperature (2-629 days) or extracts at -80°C (7-639 days), and variation of extract storage temperature (-20°C and -80°C) for long time storage (1.5 years) on the outcome of allergen quantification were tested for about 150 EDCs. The allergens on EDC cloths increased proportionally with deployment time, and allergen loads on parallel sampled tissues were significantly correlated (P < 0.0001, Pearson of log-transformed values 0.91-0.99). Extraction without Tween reduced all results (P < 0.0001, -51% DM, -85% Dp, -60% Tp, -99% Fel d 1, -86% Can f 1, -52% Mus m 1), and borate buffer resulted in lower yields of Mus m 1 (-53%), DP (-45%), and Tp (-27%) than phosphate buffer. Storage of cloths at room temperature significantly decreased Can f 1 levels (P < 0.0001, -4.8% loss for every 30 days), whereas storage of extracts at -80°C decreased DM results (P < 0.0001, -1.2% loss for every 30 days). Extracts stored at -20°C gave at mean 12% higher DM results compared to extracts stored at -80°C for 1.5 years. Several mammalian allergens and also DM antigens could be quantified reproducibly on EDCs from indoor environments. Allergen levels on EDC cloths increased proportionally with deployment time in a period of 4 weeks. Allergen yields are strongly influenced by the extraction procedure; the use of detergent Tween 20 and phosphate buffer is recommended.

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.

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.

Animal allergens and their presence in the environment.

Exposure to animal allergens is a major risk factor for sensitization and allergic diseases. Besides mites and cockroaches, the most important animal allergens are derived from mammals. Cat and dog allergies affect the general population; whereas, allergies to rodents or cattle is an occupational problem. Exposure to animal allergens is not limited to direct contact to animals. Based on their aerodynamic properties, mammalian allergens easily become airborne, attach to clothing and hair, and can be spread from one environment to another. For example, the major cat allergen Fel d 1 was frequently found in homes without pets and in public buildings, including schools, day-care centers, and hospitals. Allergen concentrations in a particular environment showed high variability depending on numerous factors. Assessment of allergen exposure levels is a stepwise process that involves dust collection, allergen quantification, and data analysis. Whereas a number of different dust sampling strategies are used, ELISA assays have prevailed in the last years as the standard technique for quantification of allergen concentrations. This review focuses on allergens arising from domestic, farm, and laboratory animals and describes the ubiquity of mammalian allergens in the human environment. It includes an overview of exposure assessment studies carried out in different indoor settings (homes, schools, workplaces) using numerous sampling and analytical methods and summarizes significant factors influencing exposure levels. However, methodological differences among studies have contributed to the variability of the findings and make comparisons between studies difficult. Therefore, a general standardization of methods is needed and recommended.

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.

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 ß-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) (ß-1,3-glucan). The ELISAs were able to detect antigens in 43% (Af), 37% (Pc), 94% (Ch), or 100% (ß-1,3-glucan) of the 124 airborne dust samples. Inhalable dust, ß-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.

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.

Rapid one-step assays for on-site monitoring of mouse and rat urinary allergens.

Allergy to rodent proteins is common among laboratory animal workers. Sensitive methods to measure exposure to these allergens have been developed. These assays are, however, expensive, time-consuming, and require a laboratory facility and methodological expertise. A simple method to screen for allergen spread, or to test whether hygiene standards are maintained, would be useful. Lateral flow immunoassays (LFIAs) are especially suited for field settings; the tests are simple and results are visible within minutes. LFIAs were developed for detection of the rodent urinary allergens Mus m 1 and Rat n 1. Pilot studies were performed in animal facilities in three countries using both extracts from airborne dust samples and samples collected by wiping surfaces. For comparison and determination of sensitivity, the concentrations of rodent urinary allergens in the samples were also measured using enzyme immunoassays (EIAs). The LFIAs for rat and mouse urinary allergens had a detection limit of 31 pg allergen per mL in a buffer system with purified allergen standards. Results of environmental dust extracts tested in LFIAs correlated well with levels obtained using EIAs. Spread of rodent allergens, or non-adherence to hygiene around laboratory animal facilities, may aggravate rodent allergy. Using a simple, sensitive one-step assay, allergens can be detected to prevent allergen exposure. The results reveal that the rapid assays are suited for on-site demonstration of exposure to rodent allergens, and thus, useful in occupational hygiene practice.