Laboratory animal allergy: a British perspective on a global problem

How Working Tasks Influence Biocontamination in an Animal Facility

The exposure to biocontaminants in animal facilities represents a risk for developing infectious, allergic and toxic diseases. The aim of this study was to determine what factors could be associated with a high level of exposure to biological agents through the measure and characterization of airborne fungi, bacteria, endotoxin, (1,3)-β-d-glucan and animal allergens. Airborne microorganisms were collected with an air sampler and identified by microscopic and biochemical methods. Endotoxin, (1,3)-β-d-glucan, Mus m 1, Rat n 1, Can f 1, Fel d 1, Equ c 4 allergens were detected on inhalable dust samples by Kinetic LAL, Glucatell, and ELISA assays, respectively. Our data evidenced that changing cages is a determinant factor in increasing the concentration of the airborne biocontaminants; the preparation of bedding and distribution of feed, performed in the storage area, is another critical working task in terms of exposure to endotoxins (210.7 EU/m3) and (1,3)-β-d-glucans (4.3 ng/m3). The highest concentration of Mus m 1 allergen (61.5 ng/m3) was observed in the dirty washing area. The detection of expositive peaks at risk of sensitization (>2 μg/g) by Fel d 1 in animal rooms shows passive transport by operators themselves, highlighting their role as vehicle between occupational and living environments.

Biological occupational allergy: Protein microarray for the study of laboratory animal allergy (LAA)

Background

Laboratory Animal Allergy (LAA) has been considered a risk for the workers since 1989 by the NIOSH. About one third of the Laboratory Animal Workers (LAWs) can manifest symptoms to LAA as asthma, rhinitis, conjunctivitis and cutaneous reactions. The prevalence of LAA-induced clinical symptoms has been estimated with a great variability (4-44%) also due to the different methodologies applied.

Objective

Evaluate the prevalence of IgE positivity to mouse and rat allergens in LAWs and assess which factors are predisposing to sensitization among subjects exposed to laboratory animals in the workplace.

Methods

One hundred LAWs were invited to fill out a questionnaire regarding current allergic symptoms, atopic history, home environment, previous and current occupational history. IgE reactivity versus specific allergens was evaluated with ImmunoCAP ISAC.

Results

Out of one hundred LAWs, 18% had a serum susceptibility to mouse and/or rat allergens and 42% reported to have occupational allergy symptoms. Combining the results acquired by ImmunoCAP ISAC and questionnaire, 17% of LAWs have been defined as LAWs-LAA positive since they present a positive IgE response and allergy symptoms, 1% LAWs-LAA sensitized, 25% LAWs-LAA symptomatic and 57% LAWs-LAA negative. Presence of previous allergy symptoms in work and life environment were significantly related to LAWs-LAA positive/sensitized.

Conclusions

The study aimed to define the immunological profile of LAWs using the proteomic array as an innovative approach in the study of environmental and occupational exposure to allergens. We suggested a definition of LAWs-LAA considering serum IgE response and presence of allergy symptoms. The proposed approach has the advantage to provide a standard methodology for evaluating the specific IgE responsiveness to animal allergens in specific workplace also considering the immunological profile of workers referred to exposure in life and occupational environment.

Exposure to flour dust in the occupational environment

Exposure to flour dust can be found in the food industry and animal feed production. It may result in various adverse health outcomes from conjunctivitis to baker's asthma. In this paper, flour dust exposure in the above-mentioned occupational environments is characterized and its health effects are discussed. A peer-reviewed literature search was carried out and all available published materials were included if they provided information on the above-mentioned elements. The hitherto conducted studies show that different components of flour dust like enzymes, proteins and baker's additives can cause both non-allergic and allergic reactions among exposed workers. Moreover, the problem of exposure to cereal allergens present in flour dust can also be a concern for bakers' family members. Appreciating the importance of all these issues, the exposure assessment methods, hygienic standards and preventive measures are also addressed in this paper.

A risk-based approach to reducing exposure of staff to laboratory animal allergens

Within the biomedical research industry, people who work with laboratory animals may be at risk of developing laboratory animal allergy, which can lead to occupational asthma. Under UK and EU laws, employers must prevent or adequately control exposure to any hazardous substance, which includes animal allergens, so far as reasonably practicable, for the protection of all people on the premises. This can be achieved in part by reviewing the risk of allergen exposure in specific areas of a facility and implementing appropriate infrastructure, environmental and performance controls to minimize that risk. The authors describe the approach used at their institution to stratify risk of allergen exposure in various areas of the animal facility and to implement appropriate controls. They also discuss their use of a monitoring program to evaluate allergen concentrations in low- and high-risk areas of the animal facility and explain how the monitoring results can be applied to determine which controls are needed to minimize risk of exposure and to provide a safe working environment.

Serial exhaled nitric oxide measurements in the assessment of laboratory animal allergy

BACKGROUND

Laboratory animal allergy (LAA) may cause eosinophilic airway inflammation, for which exhaled nitric oxide (FE(NO)) measurements are sensitive and specific. Our objective was to assess whether serial FE(NO) measurements might detect exposure-related inflammation in laboratory animal workers. METHODS. Fifty laboratory animal workers participated. Measurements of FE(NO) and spirometry were obtained at baseline (Friday) and twice-daily following a weekend with no animal contact.

RESULTS

Eleven of 50 subjects had work-related symptoms, and 2 of 11 had positive serology for LAA. Baseline FE(NO) was high (> 150 ppb) in the two seropositive subjects and increased progressively during the working week in one subject, confirming exposure-driven airway inflammation. In seronegative subjects, mean FE(NO) levels were 19.8 (standard deviation [SD], 20.1) and 21.7 (SD, 20.8) in the symptomatic and nonsymptomatic groups, respectively, with no significant changes in FE(NO) over time.

CONCLUSION

Serial FE(NO) measurements may provide complementary information in the assessment of possible occupational sensitisation. The sensitivity and specificity of this approach to diagnosing occupational asthma requires further evaluation.

Assessment of soy aeroallergen levels in different work environments

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

An amplified sandwich EIA for the measurement of soy aeroallergens

BACKGROUND

Soy hull low-molecular-weight (SHLMW) allergens were responsible for the soy asthma epidemics in Barcelona, with one 7.5 kDa protein (Gly m 1) being the main IgE-binding component. The aims of this study were to develop a sensitive sandwich enzyme immunoassay (EIA) using rabbit polyclonal antibodies to measure low levels of SHLMW allergens, and to compare this method with the previously described human IgE EIA-inhibition technique.

METHODS

IgG was isolated from serum of rabbits immunized with a chromatographically purified SHLMW extract (SHLMWE). Antibody-binding profiles were compared with those of human IgE anti-soy protein antibodies by Western blot analysis. An amplified sandwich EIA was developed using the purified SHLMWE as a calibration standard. Results were expressed in nanograms per millilitre. To compare the two assays, 54 air samples were analysed by both methods.

RESULTS

SDS-PAGE of the SHLMWE revealed four bands of 6, 8, 15 and 17 kDa. Gly m 1 in the SHLMWE was identified by fingerprinting. The detection limit of the assay was 40 pg/mL. The two methods correlated well (r=0.89; P<0.001). The allergen concentration was detected in all 54 (100%) samples by the sandwich EIA but in only 37 (68.5%) by the EIA inhibition.

CONCLUSIONS

The amplified sandwich EIA for SHLMW components has a high sensitivity and appeared to be a useful tool for the measurement of airborne SHLMW allergens, even at relatively low concentrations. Moreover, the method uses rabbit antibodies at high dilutions and does not require human sera, with limited availability and quantitative and qualitative pool-to-pool variability.

Environmental detection of mouse allergen by means of immunoassay for recombinant Mus m 1

BACKGROUND

Mouse urinary allergens are an important cause of occupational asthma in animal facilities. Domestic exposure to mouse allergens is a risk factor for asthma among inner-city residents.

OBJECTIVE

We sought to develop a sensitive and specific assay for assessing environmental mouse allergen exposure.

METHODS

An ELISA for recombinant (r)Mus m 1 was developed by using rabbit polyclonal antibodies to rMus m 1 that were affinity purified against the natural allergen. Assay specificity was established by means of immunoblotting and ELISA. Mus m 1 levels in mouse, other mammalian allergenic products, and house dust samples from inner-city homes were compared.

RESULTS

Polyclonal antibodies to Mus m 1 showed a single 20-kd band on immunoblots against rMus m 1 and male mouse urine. Parallel dose-response curves were obtained by using mouse urine extract and natural Mus m 1 or rMus m 1. Mus m 1 was detected in mouse allergenic products (0.10-10.0 microg/mL) and in gerbil allergenic products (0.1 microg/mL) but was less than the limit of detection in epithelial extracts from 10 other animal species. Environmental measurements showed an excellent correlation between Mus m 1 levels in house dust extracts from inner-city asthma studies by using 2 different Mus m 1 standards (n=22; r=0.99; P <.001).

CONCLUSIONS

A highly sensitive ELISA has been developed with rMus m 1. This assay is suitable for monitoring domestic and environmental exposure to mouse urinary allergens.

Detection of mouse and rat urinary aeroallergens with an improved ELISA

BACKGROUND

Risk analysis of laboratory animal work presupposes allergen monitoring with sensitive methods. Commercial ELISA kits have recently become available for the detection of mouse (Mus m 1) and rat (Rat n 1) urinary allergen from settled dust samples and air samples with high allergen levels.

OBJECTIVE

Our aims were to enhance the sensitivities of the commercial ELISA kits for low aeroallergen levels (less than 1 ng/m(3)) and to test these methods with air samples collected from an animal facility.

METHODS

Personal and stationary air samples were collected from an animal facility during various tasks of laboratory animal work and from various premises of the animal facility.

RESULTS

The sensitivities of the ELISA assays were improved with a careful choice of analysis parameters and reagents. The detection limits of 0.1 ng/m(3) for Mus m 1 and 0.8 ng/m(3) for Rat n 1 were established. The sensitized assays enabled detection of mouse and rat aeroallergens also from premises in which animals or dirty cages were not present during sampling.

CONCLUSION

These sensitive assays will help to perform risk assessment in laboratory animal work. However, there remains a lack of standardized analytic procedures and occupational exposure limits for laboratory animal allergens.

Laboratory animal allergy: an update

Allergic reactions are among the most common conditions affecting the health of workers involved in the care and use of research animals. Between 11 and 44% of the individuals working with laboratory animals report work-related allergic symptoms. Of those who become symptomatic, 4 to 22% may eventually develop occupational asthma that can persist even after exposure ceases. Allergic symptoms consist of rashes where animals are in contact with the skin, nasal congestion and sneezing, itchy eyes, and asthma (cough, wheezing, and chest tightness). The generation of immunoglobulin E (IgE) antibodies is a prerequisite for the production of allergic symptoms. The mechanism by which IgE antibodies develop is becoming clearer. The propensity to produce IgE is genetically determined, and pre-existing allergy may be a risk factor for the development of laboratory animal allergy (LAA). However, exposure to animal allergens is the major risk factor for the development of LAA. Techniques to measure the airborne concentration of laboratory animal allergens have been developed. Research on animal allergens themselves indicates that many of the mouse and rat urinary proteins belong to a family of proteins called lipocalins, which share sequence homology with antigens of the parasitic agent that causes schistosomiasis. The fact that parasite infections also trigger IgE antibody responses may account for the development of LAA in persons who have never had any previous allergy. The prevention of LAA should be a major goal of an effective health and safety program in the animal research facility, and it can be accomplished by education and training of employees, reduction of exposure (including the use of personal protective gear), and changes in facility design. Medical surveillance programs can also play a role in improving health of individuals working with laboratory research animals. Early recognition of symptoms and evidence of sensitization can lead to interventions to reduce exposure and thereby avoid the long-term health consequences of LAA.

Primary and secondary allergies to laboratory animals

Although laboratory animal allergy (LAA) is a significant occupational hazard among workers exposed to laboratory animals, few studies have evaluated long-term risks to workers who remain in the workplace. This short-term focus has obscured the evaluation of subsequent animal allergies (secondary LAA). We analyzed surveillance data from a 10-year LAA prevention program to estimate incidence rates of primary and secondary LAA and to evaluate the effectiveness of the prevention program in reducing the development of primary LAA. The 10-year incidence rates of primary and secondary LAA were 1.34 (95% CI, 0.78-1.90) and 11 (95% CI, 7.4-14.6) cases per 100 person-years, respectively. The annual incidence of primary LAA was reduced from 3.6% to 0 in the first 5 years and did not rise above 1.2% over the remaining years, whereas the incidence of secondary LAA was greater than 8% in most years. These findings suggest that programs effective at preventing primary LAA may need to be evaluated for their effectiveness at protecting against further risk.

Chronic obstructive lung diseases and occupational exposure

The scope of this review is to highlight important and interesting articles in the field of the epidemiology of chronic obstructive pulmonary disease and occupational exposure. Relevant information from the literature published within the past year, either on general population samples or on workplaces, indicates that a substantial proportion of asthma and chronic obstructive pulmonary diseases are work related. Methods of investigation include self-reported or interview-obtained questionnaires, job title and job exposure matrix, as well as voluntary or mandatory notifications. Furthermore, data on lung function and immunological tests are available. Specific settings and agents are quoted that have been indicated or confirmed as being linked to chronic obstructive pulmonary disease. In conclusion, occupational exposure to dusts, chemicals and gases will be considered an established, or supported by good evidence, risk factor for chronic obstructive pulmonary disease. The implications of this substantial occupational contribution to asthma and chronic obstructive pulmonary disease must be considered in research planning, in public policy decision-making, and in clinical practice.

Controlling exposure to laboratory animal allergens

Laboratory animal allergy (LAA) is a significant occupational disease that may affect up to one third of personnel exposed to laboratory animals. Research has characterized the relative risks of exposure, in terms of intensity, frequency, and duration, associated with given tasks and work areas in the animal facility. Studies have shown that reduced exposure to animal allergens can reduce the incidence of LAA and relieve symptoms among affected workers. A combination of measures to eliminate or control allergen exposure, including engineering and administrative controls and personal protective equipment, have been integral components of effective LAA management programs. The author provides a comprehensive review of exposure control options, considerations, and " best practices" relative to laboratory animal allergen in the context of traditional industrial hygiene methods.