Original articleIgE and IgG-immune mechanisms do not mediate occupation-related respiratory or systemic symptoms in hog farmers☆
Abstract
To determine the frequency and possible immunologic etiology of respiratory and other symptoms after hog barn exposure, we studied 41 hog farmers and their family members. Participants completed questionnaires and provided serum samples for measurement of IgE and IgG antibodies to hog-derived antigens, hog feed, and hog barn dust. Symptoms after hog barn exposure were reported by 85% of participants. Elevated IgE antibody levels to hog pelt, hog urine, and hog serum were found in only one individual; however, skin tests with these materials were negative. By radioimmunoassay, elevated IgG antibody levels to hog barn dust and/or hog feed were found in seven individuals; two of these sera contained precipitating antibodies to hog barn dust and hog feed. In no case could the presence of IgE or IgG antibodies be correlated with symptoms. Thus it appears that neither IgE nor IgG humoral immune mechanisms mediate respiratory or other symptoms in hog barn workers.
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Can bacterial endotoxin exposure reverse atopy and atopic disease?
2004, Journal of Allergy and Clinical ImmunologyCitation Excerpt :This novel extension of the hygiene hypothesis is based on a number of epidemiologic observations that cannot be explained by primary protective effects alone. For example, several studies have shown a low prevalence among adult or adolescent farmers of allergic symptoms, atopic sensitization, or both.26-29 This could be due to childhood exposures, but one study also showed a decreased prevalence among adolescent farmers who were not raised on a farm,30 suggesting that current exposures might play a role as well.
Studies have shown that endotoxin exposure in childhood is associated with a reduced risk of atopy and atopic asthma. It is commonly assumed that these effects only occur in early life. However, recent epidemiologic studies suggest that immune deviation might take place throughout life. Assuming that the immune system is not fixed after the first years of life, we hypothesize that endotoxin exposure might not only inhibit the development of atopic sensitization and disease at any time throughout life but might also reverse this process. This novel extension of the hygiene hypothesis is primarily based on the indirect evidence of several epidemiologic observations showing a reduction in atopy in adults highly exposed to endotoxin that is unlikely to be explained by protective effects alone. In addition, some animal studies demonstrated the potential of endotoxin to downregulate pre-existing airway eosinophilia and hyperreactivity. However, there is currently little direct evidence that endotoxin might reverse atopy and allergic diseases. Observational studies and randomized trials to test this hypothesis could ultimately lead to the development of novel treatments for atopic diseases, such as allergic asthma, hay fever, and eczema.
Allergies to the main domestic mammals and their treatment
1997, Revue Francaise d'Allergologie et d'Immunologie CliniqueLe plus grand confinement à l'intérieur des habitations et l'augmentation du nombre des animaux gardés à domicile laisse penser que l'exposition vis-à-vis des allergènes d'animaux a dû progresser au cours des 20 dernières années. Ainsi, les allergies vis-à-vis des mammnifères domestiques représentent une part de la pathologie respiratoire allergique de plus en plus importante, particulièrement chez l'enfant. L'allergène majeur du chat (Fel d 1) est celui qui est le plus fréquemment responsable de sensibilisation vis-à-vis des mammifères. Les principales sources d'allergènes sont les glandes sébacées, et la salive. Cependant, les glandes anales en contiendraient également de grandes quantités. La production de Fel d 1 serait sous contrôle hormonal et Fel d 1 pourrait être une protéine porteuse de phéromone. Dans l'air, Fel d 1 est porté par des particules dont certaines ont un diamètre aérodynamique inférieur à 5 μm. Il est possible de diminuer les concentrations aériennes de Fel d 1 dans une habitation qui abrite un chat, mais également d'obtenir chez des patients monosensibilisés au chat, une amélioration clinique en appliquant ces méthodes d'éviction. La désensibilisation vis-à-vis des allergènes du chat permet d'obtenir une diminution de la réactivité bronchique sans amélioration clinique évidente. L'allergène du chien est Can f 1. Les sources sont le pelage, la salive et la peau. Can f 1 est porté par des particules dont 20 % ont un diamètre aérodynamique de moins de 5 μm. Parmi les rongeurs, l'allergène majeur de la souris, Mus m 1 est retrouvé dans la salive, les follicules pileux et les urines, ceux du rat sont présents dans les urines et les allergènes majeurs du cobaye, Cav p 1 et Cav p 2 sont retrouvés dans le pelage. L'un des trois allergènes majeurs du cheval Equ c 1 présente des homologies avec l'allergène majeur de la souris. Les allergènes du boeuf (Bos d 1, Bos d 2, Bos d 3) se trouvent dans la peau et les squames, alors que ceux du porc se trouveraient plutôt dans les urines et la peau. Grâce aux travaux récents de biologie moléculaire objectivant d'importantes homologies structurelles et fonctionnelles entre les différentes molécules d'allergènes majeurs de mammifères, l'observation clinique courante de cosensibilisation entre différentes espèces de mammifères semble trouver son explication. De plus, cette communauté structurelle semble également se retrouver dans l'étude du comportement aérodynamique des allergènes majeurs des mammifères.
The increasing confinement inside homes and the increasing number of domestic animals suggest that exposure to animal allergens must have increased over the last 20 years. For example, allergies to domestic mammals represent an increasingly large proportion of allergic respiratory diseases, particularly in children. The major allergen of cats (Fel d 1) is the allergen most frequently responsible for sensitization to mammals. The main sources of allergens are sebaceous glands and saliva. However, anal glands also contain large quantities. Fel d 1 production is hormone-dependent and Fel d 1 could be a pheromone-transporting protein. In air, Fel d 1 is carried by particles, some of which have an aerodynamic diameter less than 5 μm. Air concentrations of Fel d 1 in a house containing a cat can be decreased and clinical improvement of patients monosensitized to cat allergens can be achieved by applying these eviction methods. Desensitization to cat allergens allows reduction of bronchial reactivity with no obvious clinical improvement. The dog allergen is Can f 1, present in the animal's coat, saliva and skin. Can f 1 is carried by particles, 20 % of which have an aerodynamic diameter of less than 5 μm. Among rodents, the major murine allergen, Mus m 1, is present in saliva, hair follicles and urine, while rat allergens are present in urine and guinea-pig major allergens, Cav p 1 and Cav p 2 are present in the coat. One of the three major equine allergens, Equ c 1, presents homologies with the major murine allergen. Bovine allergens (Bos d 1, Bos d 2, Bos d 3) are found in the skin and squames, while porcine allergens tend to be found in urine and skin. Recent molecular biology studies demonstrating important functional and structural homologies between the various major mammalian allergen molecules have provided an explanation for the common clinical observation of cosensitization between various mammalian species. This structural homology also appears to be found in the study of the aerodynamic behaviour of major mammalian allergens.
Respiratory disorders in agriculture
1993, Tubercle and Lung DiseaseWork in agriculture is associated with exposure to respiratory biohazards. The most important airborne substances include grain dust and its constituents, bacteria and metabolites (endotoxin), fungi and metabolites (glucan), and storage mites. The degree of dysfunction in exposed persons depends on the biological potency and concentration of exposure as well as on individual susceptibility. Airborne contaminants frequently occur in concentrations and compositions that challenge the defence mechanisms of the lung. This may be of particular importance in the case of susceptible workers and minors, whose exposure by the virtue of family-type operations is difficult to avoid.
Epidemiological and clinical studies have contributed to the identification of associations between respiratory disorders and agricultural exposures. Chronic bronchitis, asthma, hypersensitivity pneumonitis, organic dust toxic syndrome and chronic airflow limitation have been found to occur in agricultural workers. Clinical and experimental studies have advanced the understanding of immunologic and non-immunologic mechanisms involved in respiratory responses to a wide spectrum of inhaled organic dusts.
Although the evidence has provided substantial insight into the occurrence and pathogenesis of respiratory disorders in agriculture, further investigation is necessary. There is a need for research involving accurate assessment of exposures and their respiratory effects. There is also a need for the establishment of preventive programs, with emphasis on reduction of harmful exposures. Increasing concern about respiratory disorders in agriculture justifies further scientific effort in both areas.
Le travail agricole comporte une exposition à des risques biologiques respiratoires. Les aérocontaminants les plus importants comprennent la poussière de grain et ses composants, des bactéries et leurs métabolites (endotoxines), des moisissures et leurs métabolites (glucan) et des ‘mites’ liées au stockage. Le degré des désordres fonctionnels chez les sujets exposés dépend du pouvoir biologique et de la concentration de l'exposition, ainsi que de la susceptibilité de l'individu. Les aérocontaminants se présentent souvent à des concentrations et selon des teneurs qui mettent en jeu les mécanismes de défense du poumon. Ce fait pourrait être d'une particulière importance dans les cas de travailleurs prédisposés et de sujets mineurs dont l'exposition en vertu d'exploitation de type familial est difficile à éviter.
Des études épidémiologiques et cliniques ont contribué à l'identification d'associations entre des maladies respiratoires et des contacts environnementaux agricoles. Bronchite chronique, asthme, pneumopathies d'hypersensibilité, syndrome toxique des poussières organiques et limitation chronique du débit respiratoire ont été trouvés chez des ouvriers agricoles. Les études cliniques et expérimentales ont fait progresser la compréhension des mécanismes immunologiques et non-immunologiques impliqués dans les réponses respiratoires à un large spectre de poussières organiques inhalées.
Bien que l'on dispose d'un aperçu substantiel sur l'apparition et la pathogénie des désordres respiratoires en milieu agricole, une recherche plus poussée est nécessaire. Il existe un besoin d'évaluation précise des expositions et de leurs effets respiratoires. La nécessité s'impose également d'établir des programmes de prévention centrés sur la réduction des expositions nocives. Une implication croissante des maladies respiratoires dans l'agriculture justifie un effort scientifique ultérieur accru dans les deux domaines.
El trabajo agrícola expone a riesgos biológicos respiratorios. Los contaminantes aéreos más importantes son el polvo de granos y sus constituyentes, bacterias y sus metabolitos (endotoxinas), hongos y sus metabolitos (glucan) y ácaros en relación al almacenamiento. El grado de alteración funcional en las personas expuestas depende de la potencia biológica y de la concentración de la expositión, así come de la susceptibilidad del individuo. Los contaminantes aéreos se presentan frecuentemente en una concentración y compositión que compromete los mecanismos de defensa del pulmón. Esto podría ser de particular importancia en el caso de trabajadores susceptibles y de niños, cuya exposición es difícil de evitar a causa de la explotación de tipo familiar.
Estudios epidemiológicos y clínicos han contribuido a la identificación de asociaciones entre enfermedades respiratorias y la exposición agrícola. En trabajadores agrícolas se ha observado bronquitis crónicas, asma, neumonitis de hipersensibilidad, síndrome tóxico de polvos orgánicos y limitación crónica del flujo respiratorio. Los estudios clínicos y epidemiológicos han permitido avanzar en la comprensión de los mecanismos inmunológicos y no inmunológicos implicados en la respuesta respiratoria a un amplio espectro de polvos orgánicos inhalados.
Aunque se dispone de pruebas sustanciales sobre la aparición y la patogénesis de los trastornos respiratorios en medio agrícola, se necesita aún investigaciones más profundas. Se requiere una investigación para evaluar en forma precisa los efectos respiratorios de la exposición. Se necesita igualmente establecer programas de prevención centrados en la reducción de las exposiciones nocivas. La importancia creciente de los trastornos respiratorios en el medio agrícola justifica un esfuerzo científico mayor en ambas áreas.
Immunological and respiratory findings in swine farmers
1991, Environmental ResearchThe prevalence of respiratory symptoms and ventilatory capacity abnormalities in relation to immunological status was studied in 32 swine farmers and in 39 controls. A large number of swine farmers reacted to swine confinement building antigens (swine hair, 34%, swine confinement agents, 28%) but also to other extracts such as animal food (78%) and corn flour (37%). Control workers also reacted to these antigens in similar frequencies. Increased serum IgE levels were found in 3 swine farmers (9.4%) and all 3 had positive skin tests to at least one of the swine antigens. Among control workers one (2.6%) had an increased serum IgE level; this worker exhibited a positive skin reaction to swine food antigen. Swine farmers with positive skin reactions had across-shift reductions of FEF50 and FEF25 significantly larger than those with negative skin tests (P < 0.01). Preshift measured ventilatory capacity data (FEV1, FEF50, FEF25) in swine farmers with positive skin tests were significantly lower (compared to predicted) than in those with negative skin tests. Additionally, we showed that a water-soluble swine confinement building antigen causes a dose-related contraction of nonsensitized guinea pig trachea smooth muscle studied in vitro. Our data indicate significant differences in lung function between swine workers with positive and negative skin tests. We suggest that skin testing may be helpful in identifying workers at risk for developing lung disease.
A respiratory questionnaire, pulmonary function tests, and an examination of airways responsiveness were conducted on 20 swine farmers and 20 control subjects. The swine farmers represented almost the complete work force from 13 Hutterite colonies and had worked in confinement buildings with more than 2,000 swine (3,270 ± 1,221 swine) for at least four hours (6.6 ± 1.8 hours) per day for more than two years (10.5 ± 7.5 years). The control subjects were randomly selected from outdoor city workers from the city of Saskatoon and were matched for gender, age (± 2 years), and smoking status. Eleven swine farmers (55 percent) had chronic cough, compared with three (15 percent) of the control subjects (p<0.01). Eight (40 percent) of the swine farmers had symptoms of wheezing, compared with three (15 percent) of the control subjects (p<0.05). The FEV1 was significantly lower in swine farmers (97.2 ± 11.5 percent predicted) than in control subjects (106.0 ± 12.0 percent of predicted) (p<0.05). Airways responsiveness was measured by methacholine challenge with doubling concentrations ranging from 0.25 to 256 mg/ml. The provocation concentrations resulting in a reduction of 10 percent (PC10) and 20 percent (PC20) in FEV1 were lower in swine farmers than in control subjects (PC10, 77.2 ± 78.8 mg/ml vs 180.8 ± 96.5 mg/ml; p<0.01; and PC20, 154.5 ± 99.9 mg/ml vs 229.6 ± 66.8 mg/ml; p<0.05). Twelve swine farmers (60 percent) had PC20 of less than 256 mg/ml, compared with three (15 percent) of the control workers (p<0.01). Fewer swine farmers demonstrated atopy as measured by skin prick tests than did control workers (21 percent vs 56 percent; p<0.05). These findings suggested that occupational exposure in swine confinement buildings is associated with mild increases of nonspecific, nonatopic airways responsiveness in swine farmers.
Airway diseases due to organic dust exposure
2013, Asthma in the Workplace, Fourth Edition
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Supported by a grant from the Mayo Foundation.