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Introduction: There are conflicting data on the association between early exposure to pets and allergic diseases. Bias related to retrospective information on pet ownership has been addressed as a reason for distorted study results., Objective: To elucidate how early exposure to cat and dog relates to IgE-sensitization and asthma in children at 2 and 4 years of age, in a prospective birth-cohort study., Methods: Four thousand and eighty-nine families with children born 1994-1996 in predefined areas of Stockholm answered questionnaires on environmental factors and symptoms of allergic disease at birth, one, two and four years of age. Dust samples collected from the mothers' beds at birth were analysed for Fel d 1 and Can f 1 in a subgroup of the cohort. Blood samples taken at four years from 2614 children were analysed for allergen-specific IgE to common airborne allergens. Risk associations were calculated with a multiple logistic regression model, with adjustment for potential confounders., Results: A correlation was seen between allergen levels and reported exposure to cat and dog. Exposure to cat seemed to increase the risk of cat sensitization, OR (odds ratio) 1.44 (95% confidence interval 1.03-2.01), whereas dog exposure did not have any effect on dog sensitization, OR 1.16 (0.79-1.72). Dog ownership was related to a reduced risk of sensitization to other airborne allergens, OR 0.36 (0.15-0.83), and a similar tendency was seen for cat ownership OR 0.63 (0.37-1.07). Early dog ownership seemed to be associated with a lower risk of asthma, OR 0.50 (0.24-1.03), with no corresponding effect after cat ownership, OR 0.88 (0.56-1.38)., Conclusion: Early exposure to cat seems to increase the risk of sensitization to cat but not of asthma at 4 years of age. Dog ownership, on the other hand, appears to be associated with lowered risk of sensitization to airborne allergens and asthma. Both aetiological relationships and selection effects have to be considered in the interpretation of these findings.

Background: Exposure to furred pets in early life has been considered to increase the risk of allergic sensitization and consequent development of asthma later in children. However, recently, it has been suggested that early exposure to pets prevents sensitization. The aim of this study was to evaluate the importance of early exposure to pets and other environmental risk factors in asthmatic children., Methods: This is a follow-up study after 2 years of a previously investigated group of 193 asthmatic children, aged 1-4 years. The study was completed by 181 children, who were clinically examined; serum IgE antibodies were also measured and a questionnaire was answered., Results: Children with reported exposure to cats during the first 2 years of life were more likely to have developed sensitization to cat by 4 years of age than unexposed children. High levels of cat allergen (Fel d 1> or =8 microg/g dust) were associated with an increased risk of sensitization to cat and, in combination with tobacco smoke, also with the development of more severe asthma., Conclusion: In young asthmatic children, early exposure to cat and tobacco smoke increased the risk of allergic sensitization and further development of more severe asthma later in childhood.

Background: More than 95% of birch pollen-allergic subjects react with the major birch pollen allergen, Bet v 1, and almost 60% of them are sensitized exclusively to this allergen., Objective: The aim of this study was to compare the in vivo biologic activity of genetically engineered hypoallergenic derivatives of Bet v 1 (an equimolar mixture of 2 recombinant [r] Bet v 1 fragments and of rBet v 1 trimer) with that of rBet v 1 wild-type by skin prick and intradermal testing., Methods: Birch pollen-allergic patients who had not received immunotherapy (n = 23), a group of allergic patients without birch pollen allergy (n = 12), and nonatopic persons (n = 8) from northern Europe (Sweden) underwent skin prick and intradermal testing with different concentrations of the recombinant allergens and commercial birch pollen extract before the birch pollen season. Immediate and late-phase reactions were recorded and allergen-specific IgE and IgG subclass responses were determined by CAP radioallergosorbent test and ELISA, respectively., Results: Atopic persons without birch pollen allergy and nonatopic individuals did not have skin reactions to rBet v 1 wild-type and genetically engineered hypoallergenic derivatives. By intradermal testing, 8 of 23 and 13 of 23 birch pollen-allergic patients did not react with the highest concentration (1 microg/mL) of the rBet v 1 fragment mix and rBet v 1 trimer, respectively, compared with 1 with rBet v 1 wild type. Likewise, the highest concentration (100 microg/mL) of fragment mix or trimer failed to elicit a positive skin prick test in 18 of 23 and 15 of 23 patients in comparison with 0/23 with the monomer. No late reactions were observed., Conclusion: The recombinant hypoallergenic birch pollen allergens can probably be used for patient-tailored immunotherapy with a reduced risk to induce anaphylactic reactions.

Background: A selective recruitment of eosinophils to sites of allergic inflammation is suggested to be controlled by regulation of cytokines, chemokines and adhesion molecules., Objective: The aim of this study was to examine whether allergen challenge in skin chambers, applied on patients with allergic rhinitis and mild asthma, results in a selective influx of activated eosinophils and detectable levels of cytokines/chemokines related to eosinophil recruitment, such as interleukin (IL)-5 and eotaxin., Methods: A skin blister was induced on the volar aspect of each forearm; one contained PBS-heparin buffer (control) and the other was challenged with relevant allergen. Peripheral blood was drawn before the allergen was applied to the skin chamber, and the expression of CD9, CD11b and EG2-epitope on intracellular eosinophil cationic protein (ECP) was analysed in eosinophils. Chamber fluid was collected 8 h after allergen application and analysed for differential cell counts, expression of eosinophil activity markers, the presence of ECP, eotaxin, and IL-5., Results: The number of recruited leucocytes was equal in the allergen-challenged chambers and in controls. However, the number of eosinophils was significantly increased in the allergen-challenged chambers, and elevated levels of released ECP were measured. Moreover, the eosinophils recruited were activated, as shown by increased expression of EG2 and CD11b, and decreased expression of CD9, in comparison with blood eosinophils. In the skin chamber fluids, higher levels of eotaxin were detected in the allergen-challenged chambers than in controls, but there were no detectable levels of IL-5., Conclusion: We have demonstrated a selective recruitment of eosinophils, and higher levels of released ECP and eotaxin, in skin chambers stimulated with allergen, as compared with control chambers. Allergen challenge in skin chambers is a useful tool for studies of eosinophil recruitment, their state of activation, and their involvement in the allergic inflammatory response.

Background: Earlier studies have shown a high prevalence of respiratory symptoms in farming communities and that storage mites constitute important allergens. We examined risk factors associated with asthma and rhinoconjunctivitis among Swedish farmers., Methods: A population of 1015 small-scale dairy farmers was part of an epidemiologic survey. After selection based on symptom reports in a questionnaire, 461 of the farmers attended a medical examination, which comprised SPT, RAST analyses, and lung-function measurements. Risk factors for sensitization to different allergens, and development of asthma and rhinoconjunctivitis were assessed by multiple logistic regression., Results: The prevalence of atopy was 26.7% among the farmers. For both asthma and rhinoconjunctivitis, sensitization to mites (OR = 5.8 vs. OR = 3.8) and pollens (OR = 10.3 vs. OR=5.8) was a significant risk factor. There was a significant relationship between sensitization to mites and working time (OR = 5.2). Environmental tobacco smoke and exposure to different animal species at the farm did not appear to affect the risk of allergen sensitization or respiratory symptoms. Farmers smoked less than the general population, but they more frequently had reduced FEV1., Conclusions: Allergen sensitization, especially to mites and pollens, was significantly associated with asthma and rhinoconjunctivitis in a farming community. The results point to allergen avoidance as a major goal for the prevention of occupational respiratory diseases among the farming population.

Background: The increasing prevalence of asthma and allergy in many countries demands evaluation of potential risk factors to improve the possibility of prevention., Objective: We studied the association between exposure to cat and dog allergen and allergic sensitization in young children with asthma and interactions with potential environmental risk factors., Methods: One hundred eighty-nine young children with asthma were evaluated. IgE antibodies to cat and dog were analyzed. Questionnaires were filled in focusing on exposure to cats and dogs, environmental tobacco smoke (ETS), and signs of home dampness as indicated by window pane condensation (WPC) during the first years of life. House dust was analyzed for content of cat (Fel d 1) and dog (Can f 1) allergen., Results: There was a strong association between the degree of reported exposure to cat and dog and the concentration of the respective allergens in floor dust. A dose-response relationship was found between cat exposure, measured as either reported degree of cat exposure or cat allergen levels in dust, and sensitization both to cat and dog. No such relationship was found between exposure and sensitization to dog. WPC increased the risk for sensitization to cat (odds ratio = 2.6, 95% confidence interval 1.2-5.8), whereas ETS strongly tended to do so both to cat and dog. Interaction was found between exposure to ETS, WPC, and high levels of cat allergen (>8 microg/g dust). The presence of all 3 risk factors revealed a multiplicative interaction with a high risk of sensitization to cat (odds ratio = 42.0, 95% confidence interval 3.7-472.8)., Conclusions: Keeping cats indoors may be a health hazard for infants and young children at risk for development of asthma, particularly when they live in a damp house and their parents smoke.

Background: Earlier studies have shown that farmers are to a low degree sensitized to animal allergens. We have measured the amount of cat (Fel d 1) and dog (Can f 1) in farm households and examined the relationship between exposure and sensitization to cat and dog allergens., Methods: Dust samples from the homes of 403 farmers who had participated in an epidemiologic follow-up study on respiratory symptoms were analyzed for allergen content by two-site ELISA methods., Results: Fel d 1 was detected in 99.5% of the farmers' households ranging from 0.055 to 1455 microg/g dust in mattresses (GM 13.2) and to 3775 microg/g dust in living-room carpets (GM 17.1). Can f 1 was detected in 90.6% of the households from 0.2 to 116 microg/g dust in mattresses (GM 2.0) and to 504 microg/g dust in carpets (GM 4.3). Homes with pets present had the highest levels of the allergens (P<0.001). A total of 8.4% and 7.4% of the farmers were sensitized to cat and dog, respectively. A significant correlation was noted between exposure to the allergens and specific IgE to cat and dog, respectively (P<0.001). Sensitization to cat (OR = 4.9) and dog (OR = 17.8) was significantly associated with asthma., Conclusions: In spite of the abundance of Fel d 1 and Can f 1, farmers are only to a low degree sensitized to cats and dogs.

Several studies have confirmed the presence of animal dander allergens in school dust but the effect of this indirect animal exposure on health has not been evaluated. In this study we investigated bronchial reactivity and markers of eosinophil activity and inflammation during two separate weeks of school in 10 children with mild asthma and a positive skin prick test to cat and dog. At the beginning and the end of the first week the children underwent bronchial challenges with methacholine, and at the beginning and the end of the second week they underwent nasal lavages (NAL) and induced sputum samplings. Blood and urine samples for analysis of inflammatory markers were obtained before and after both school weeks. Peak expiratory flow (PEF) and symptoms of asthma and allergy were recorded daily, and spirometry was performed on each visit. The exposure to animal dander allergens was estimated from dust samples obtained in the subjects' schools and homes. Bronchial sensitivity to methacholine increased in the week when this was measured. The proportion of eosinophils in peripheral blood, and urinary eosinophil protein X (EPX), decreased in both weeks. There was a trend towards an increase of eosinophil peroxidase (EPO) and myeloperoxidase (MPO) in sputum in the week when these proteins were measured. The concentrations of cat (Fel d1) and dog (Can f1) allergens were higher in dust collected in schools than in homes. Our results show that in children with mild asthma and animal dander allergy, there is a significantly increased bronchial sensitivity to methacholine after one school week. There is also a significant decrease in the number of circulating eosinophils and a trend towards an increase of sputum EPO, which could correlate with the early phase of eosinophil recruitment to the lungs. These effects may be related to the continuous exposure to animal allergens in school dust.

Background: Earlier studies from several countries have shown that IgE-mediated allergy in rural populations is of considerable importance and that storage mites are dominant allergens., Objective: In an epidemiological follow-up study among farmers on the island of Gotland, Sweden in 1996 we wished to investigate the prevalence of respiratory allergy and to find out whether storage mites are still important allergens in a farming environment., Methods: A questionnaire concerning airway symptoms, social and working conditions and smoking habits was distributed to all Gotland farmers aged 15-65 years and was completed by 1577 (86.7%), of whom 1015 were dairy farmers. Based on the answers, 500 dairy farmers were invited to undergo a medical examination which included a skin-prick test (SPT) and blood sampling for RAST analyses. Prevalence figures (symptoms, RAST and SPT) given for the whole population (n = 1015) were based on the investigation of the 461 farmers who took part in the examination., Results: Immediate onset hypersensitivity was present in 41.7% of the 1015 farmers studied, which is almost the same figure as in 1984 (40.0%). The prevalence of asthma had increased significantly during the previous 12 years (5.3% vs 9.8%), as had asthma in combination with rhinoconjunctivitis (3.7% vs 7.0%). Rhinoconjunctivitis, on the other hand, had not changed significantly (36.5% vs 33.1%) and remained one of the most common symptoms. The prevalence of storage mite allergy in the farming population in 1996 was 6.5% and constituted an important cause of allergic symptoms., Conclusion: Over 12 years, Gotland dairy farmers have developed significantly more respiratory symptoms from the lower airways, although the proportion with atopy is unchanged. Storage mites are still dominant allergens for developing allergic disease.

Dysregulation of cytokine production in atopic individuals has previously been clearly demonstrated. In the present study we aimed to assess whether a prolonged in vitro exposure of peripheral blood lymphocytes (PBMC) to allergen would result in a, by time, changed cytokine profile in allergic subjects. Blood was taken from 11 atopic asthmatic subjects and nine healthy non-atopic controls during the birch pollen season. PBMC were stimulated with birch pollen allergen (100, 1000 and 10,000 SQ-U/ml). After different times of exposure (1, 3 and 5 weeks) interleukin (IL)-5 and interferon-gamma (IFN-gamma) production was measured. Prior to the IL5 and IFN-gamma determinations, PHA was added to the cultures to ensure maximal release of cytokines. The asthmatic group always displayed a lower IFN-gamma:IL-5 ratio. Significant differences in ratio between the two groups were observed. Furthermore, PBMC challenged in vitro with 10,000 SQ-U/ml resulted in significantly elevated levels of IL-5 in the asthmatic group compared to the control group when determined after 3 and 5 weeks stimulation. In the asthmatic group the balance between IL-5 and IFN-gamma is shifted towards increased IL-5 production following prolonged in vitro stimulation. This might illustrate the in vivo situation, where an increased IL-5 production is of importance in the pathogenesis of asthma.

The study aimed to determine whether inhalation of subclinical allergen doses-leads to a shift in the balance between T helper (Th) 1 and Th2 cells in asthmatic patients. Elevated IgE requires allergen-specific T cells producing cytokines such as interleukin (IL)-4 or IL-13. Interferon-gamma (IFN-gamma) produced by Th1 cells counteracts the effects of IL-4. In nature, allergic persons are often exposed to low levels of allergen, leading to hyperreactivity, but not to acute allergic reactions. In this study, nine allergic persons inhaled low doses of allergen or placebo in a double-blind manner over seven consecutive weekdays. During the study, the bronchial responsiveness to histamine challenge increased, but no subject exhibited asthmatic symptoms. Blood was drawn on days 0, 1, 4, and 9, and the number of IL-4- and IFN-gamma-producing cells was measured by enzyme-linked immunospot (ELISPOT) assay after in vitro stimulation with a low-dose phytohemagglutinin (PHA) mixed with the relevant allergen or with PHA alone. In three of the four subjects receiving allergen, the IL-4/IFN-gamma ratio increased during the time of the study. No increase was seen in the placebo group. No increase was seen in serum IgE levels in any of the groups. We conclude that a shift in the balance between Th1 and Th2 cells can be detected in subjects exposed to subclinical allergen doses.

Bronchial provocation studies with L. destructor (L. des.) extract were made on 12 farmers with asthma who were exposed daily to stored hay and grain and had positive radio-allergo-sorbent test (RAST) to L. des. All 12 farmers developed more than a 20% fall in FEV1 to the extract. None of the symptomatic farmers who were also RAST positive to the L. des. culture medium developed an asthmatic reaction to the medium extract. Neither four healthy farmers nor two patients with asthma caused by D. pteronyssinus (D. pt.) responded to L. des. or the L. des. culture medium. Challenges with D. pt. extract were negative in two symptomatic farmers who were RAST positive to L. des. and negative to D. pt. The present study further supports our previous hypothesis that there is an IgE-mediated immunological mechanism behind L. des.-induced asthma in farmers and that atopic farmers are liable to develop occupational asthma caused by allergy to L. des..

Predatory mites are used as biological pesticides worldwide for control of spider mites and other pests in greenhouses. The aim of this study was to evaluate the impact of occupational exposure toPhytoseiulus persimilisandHypoaspis mileson IgE sensitization among a large group of Swedish greenhouse workers and to examine the relationship between exposure and allergic asthma and rhinoconjunctivitis.A total of 96 greenhouse workers from the southern part of Sweden, who were using the predatory mites for control of pests, were investigated with a questionnaire and a medical examination including lung function test. Blood samples were taken to test for allergen-specific IgE antibodies toPhytoseiulus persimilisandHypoaspis milesas well as toTetranychus urticae,Dermatophagoides pteronyssinus/farinaeandTyrophagus putrescentiae.Seventeen of the 96 workers were positive in ImmunoCAP to predatory mites: 17 toP. persimilis(17.7%) and 14 toH. miles(14.6%). Subjects sensitized to predatory mites were significantly more often atopic (13/17), defined as a positive Phadiatop, than those who lacked IgE against these mite species (17/79) (P < 0.01). IgE antibodies to the red spider miteT. urticaewere present among 23 subjects. Thirty-five of the investigated subjects displayed a positive ImmunoCAP to at least one of the investigated mite species. Furthermore, sensitization to any of the mites tested was significantly associated with asthma (OR = 9.3) and rhinoconjunctivitis (OR = 4.3).IgE sensitization to predatory mites,P. persimilisandH. miles, is common among greenhouse workers. The findings stress the importance of improved allergen avoidance in greenhouse environments. [ABSTRACT FROM AUTHOR]

Discusses various studies about dust mites, Dermatophagoides siboney and Blomia tropicalis, as possible causes of allergic disorders. Background of both species; Major risk factor for asthma; Allergenic characterization of B. tropicalis; Relation between dual immune response to pyroglyphid and non-pyroglyphid mites and crossreacting allergens; Importance of immunoglobulin E-mediated sensitization to D. siboney as a risk factor for allergic disease.

The dust mite Lepidoglyphus destructor is the dominating source of allergens giving rise to asthma and rhinitis among farmers. In a previous study of the localization of allergens in L. destructor we demonstrated that the 39 kDa allergen is associated with digestion. Here we describe the localization of the principal 15 kDa allergen and the high molecular weight allergen complex (79 and 93 kDa) in L. destructor with confocal laser scanning microscopy (CLSM). Cryostat-cut sections of mite bodies and faecal pellets were probed with mouse monoclonal antibodies (MoAbs) raised against the allergens. The 15 kDa allergen disclosed labelling of the mite body and most of the faecal pellets but left the exoskeleton unlabelled. The binding was widespread, and most intense in the mouth region. However, some staining was also observed around the gastrointestinal tract. In contrast, the 79 and 93 kDa allergen complex stained the exoskeleton and the front part of the mite. Interestingly, we detected no labelling of the faecal pellets with the MoAb against the 79/93 kDa allergen. The study indicates that the 15 kDa allergen is associated with the digestive tract whereas the function of the 79 and 93 kDa allergen complex remains to be elucidated. [ABSTRACT FROM AUTHOR]

Exposure to storage (nonpyroglyphid) mites has been increasingly recognized as a cause of asthma and rhinitis. Several species have been identified in Europe; e.g., Lepidoglyphus destructor, Acarus farris/siro, Tyrophagus spp., Glycyphagus domesticus, and Blomia tjibodas. Blomia tropicalis, on the other hand, predominates in subtropical and tropical areas. Studies from several countries have shown that IgE-mediated allergy in rural populations is of considerable importance and that storage mites are major allergens. Since these mites are found in homes, especially in regions with damp housing conditions, urban populations are at risk of becoming sensitized. Therefore, sensitization is not restricted only to those with occupational exposure. Several major allergens from storage mites have been identified and characterized. There seems to be a limited allergenic cross-reactivity between storage- and house dust mites. Molecular cloning has demonstrated that the Group 2 allergens from storage mites (Lep d 2 and Tyr p2) show more than 40% sequence identity with the Group 2 allergens from Dermatophagoides spp. The availability of a large number of recombinant dust mite allergens will make it possible to investigate their homology and the number of allergens required for the diagnosis and treatment of storage mite allergy. [ABSTRACT FROM AUTHOR]

The study aimed to determine whether inhalation of subclinical allergen doses-leads to a shift in the balance between T helper (Th) 1 and Th2 cells in asthmatic patients. Elevated IgE requires allergen-specific T cells producing cytokines such as interleukin (IL)-4 or IL-13. Interferon-gamma (IFN-γ) produced by Th1 cells counteracts the effects of IL-4. In nature, allergic persons are often exposed to low levels of allergen, leading to hyperreactivity, but not to acute allergic reactions. In this study, nine allergic persons inhaled low doses of allergen or placebo in a double-blind manner over seven consecutive weekdays. During the study, the bronchial responsiveness to histamine challenge increased, but no subject exhibited asthmatic symptoms. Blood was drawn on days 0, 1, 4, and 9, and the number of IL-4- and IFN-γ-producing cells was measured by enzyme-linked immunospot (ELISPOT) assay after in vitro stimulation with a low-dose phytohemagglutinin (PHA) mixed with the relevant allergen or with PHA alone. In three of the four subjects receiving allergen, the IL-4/IFN-γ ratio increased during the time of the study. No increase was seen in the placebo group. No increase was seen in serum IgE levels in any of the groups. We conclude that a shift in the balance between Th1 and Th2 cells can be detected in subjects exposed to subclinical allergen doses. [ABSTRACT FROM AUTHOR]

Bronchial provocation studies with L. destructor (L. des.) extract were made on 12 farmers with asthma who were exposed daily to stored hay and grain and had positive radio-allergo- sorbent test (RAST) to L. des. All 12 farmers developed more than a 20% fall in FEV, to the extract. None of the symptomatic farmers who were also RAST positive to the L. des. culture medium developed an asthmatic reaction to the medium extract. Neither four healthy farmers nor two patients with asthma caused by D. pteronyssinus (D. pt.) responded to L. des. or the L. des. culture medium. Challenges with D. pt. extract were negative in two symptomatic farmers who were RAST positive to L. des. and negative to D. pt. The present study further supports our previous hypothesis that there is an IgE mediated immunological mechanism behind L. des-induced asthma in farmers and that atopic farmers are liable to develop occupational asthma caused by allergy to L. des. [ABSTRACT FROM AUTHOR]

Summary Background Polymorphisms within the β subunit of the high-affinity receptor for IgE (FcεR1-β) on chromosome 11q13 have been related to atopy and asthma and the lymphotoxin α (LTα) gene on chromosome 6 is implicated in asthma. Objective To elucidate the association of polymorphisms in the FcεR1-β and LTα genes to IgE responses and asthma in a family-orientated rural population. Methods A total of 461 adult farmers, who participated in an epidemiological follow-up study on respiratory symptoms among farmers on the Swedish island of Gotland, were examined. The traits assessed included serum total IgE, IgE antibody responses to 21 common inhalant allergens and asthma. Results The 237G mutation was only detected in seven persons. Atopy was found to be associated with the Rsa I-ex7 AB-genotype (OR = 1.9; P = 0.04). The Rsa I-ex7 B allele had a significant influence on IgE responses to pollens and dust mites (OR = 5.5; P = 0.03 and OR = 5.2; P = 0.049, respectively). The influence of this allele was stronger when the association towards single dust mite species (Lepidoglyphus destructor ) was estimated (OR = 7.1, P = 0.03) and the association increased even more when the major allergen of L. destructor (rLep d 2) was analysed (OR = 11.2, P = 0.02). These associations were independent of sex, age and smoking, and the estimates of Rsa I-in2 independent of Rsa I-ex7. Rsa I-in2, Rsa I-ex7 and LTα genotypes were unassociated with total serum IgE. No significant difference in the distribution of Rsa I-in2, Rsa I-ex7 and LTα genotypes was found among subjects with atopy or asthma compared to healthy controls. Conclusion This study supports the notion that polymorphisms in the FcεR1-β gene have significant effects on IgE responsiveness. Secondly, dust mites in rural populations influence the expression of genes on chromosome 11q13. [ABSTRACT FROM AUTHOR]