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The existence of specific immunoglobulin E (IgE) allows us to determine the allergens that cause the allergic disease. For the purposes of allergen avoidance and immunotherapy, the measurement of specific IgE is widely applied in clinical laboratories. However, if IgE from the serum of an allergic patient exhibits reactivity to multiple allergens, it would cause a problem. The present study analyzes whether the serum IgE with multiple reactivity is due to the presence of unique IgE against the common epitope shared by different allergens or the presence of multiple IgEs against different epitopes on different allergens. The quantitative-competitive inhibition tests and the immunoblotting were applied to analyze the immunosimilarity among examined allergens. The result shows that the competitive inhibition of IgE binding between shrimp and crab allergens is higher than those between either shrimp and cockroach or between crab and cockroach. Furthermore, the results of immunoblotting are consistent with those of quantitative-competitive inhibition tests. These results allow us to detect the cross-reactivity for atopic IgE against multiple allergens.
Despite epidemiological evidence of cardiovascular complications in asthmatics, the direct contribution of asthmatic pathophysiology to cardiovascular effects is unknown. Considering parallels in underlying pathophysiology, we tested the hypothesis that presence of systemic allergy and asthma worsens the outcome of myocardial ischemia-reperfusion injury. Systemic allergy and asthma were created in rabbits by repeated intraperitoneal injections of allergen with adjuvant, followed by an airway challenge in two groups. Nonsensitized animals served as controls. In situ myocardial ischemia-reperfusion was induced in anesthetized animals by a 30-min ligation of a coronary artery, followed by 3 h of reperfusion. Ischemia-reperfusion was done at 24 h after intraperitoneal boost (1 DB) and 7 days (7 DB) after the last intraperitoneal injection and at 24 h (1DAWCH) and 7 days (7DAWCH) after airway challenge. The infarct size (determined by 2,3,5-triphenyltetrazolium chloride staining, normalized to area at risk) was significantly higher in all sensitized groups compared with control (1DB, 31 +/- 4; 7DB, 28.9 +/- 2.6; 1DAWCH, 66.1 +/- 4.1; 7DAWCH, 28.9 +/- 9.2; control, 16.7 +/- 3.2; means +/- SE; P < 0.01 by ANOVA; n = 6). The 1DAWCH group showed significantly greater infarct than all other groups (P < 0.05). Myocardial neutrophil infiltration was significantly higher in the sensitized groups compared with control (P < 0.01). Tissue neutrophil counts showed a strong positive correlation to infarct sizes (r2 = 0.9). These observations indicate that the presence of systemic allergy and asthma is associated with increased myocardial neutrophil infiltration during acute ischemia-reperfusion and increased size of the resulting infarct.
Asthma is a chronic respiratory disease affecting over 230 million people worldwide, with higher prevalence in women. Environmental allergens such as house dust mite (HDM) trigger airway inflammation and hyperresponsiveness (AHR), yet the epigenetic mechanisms underlying these responses remain poorly understood. Furthermore, the role of estrogen receptors in the context of asthma is understudied. We aimed to investigate whether estrogen receptor-specific DNA methylation contributes to HDM-induced airway remodeling and hyperresponsiveness. Male and female C57BL/6J wild-type mice and estrogen receptor α and β knockout mice (Esr1-/- and Esr2-/-) were exposed to HDM or phosphate-buffered saline for 5 wk. DNA methylation and RNA sequencing data were obtained from snap-frozen whole lung tissues. HDM exposure resulted in widespread differential methylation of genes associated with inflammation and AHR, including Itgal, Tmem267, Rap1b, Bmf, Mid1, Fgd1, Ddx4, Comtd1, Filip1l, Grb10, and Chst7. Notably, the absence of estrogen receptor β (in Esr2-/- mice) produced the most pronounced methylation patterns, particularly in females. Pathway enrichment analysis revealed asthma-relevant processes such as extracellular matrix remodeling, leukocyte adhesion and migration, airway smooth muscle contraction, and inflammatory signaling. Integration of methylation and gene expression data confirmed significant correlations (P < 0.05) for Itgal, Rap1b, and Tmem267, and a marginal correlation for Chst7 (P < 0.1), implicating these genes in allergic asthma pathogenesis. Our findings demonstrate that HDM exposure induces sex-specific epigenetic changes mediated by estrogen receptor status, highlighting a potential mechanism for increased asthma susceptibility in women. These results can inform estrogen receptor-targeted treatment strategies for allergic airway diseases.NEW & NOTEWORTHY Understanding estrogen receptor-mediated epigenetic regulation provides a foundation for developing sex-specific interventions for asthma, addressing the higher prevalence and severity observed in women. In this study, we demonstrate that exposure to house dust mite in the mouse lung is associated with epigenetic alterations in genes linked to airway hyperresponsiveness and lung inflammation. These alterations were dependent on the presence or absence of estrogen receptors.
Development of the basement membrane zone (BMZ) occurs postnatally in the rhesus monkey. The purpose of this study was to determine whether house dust mite allergen (HDMA) plus ozone altered this process. Rhesus monkeys were exposed to a regimen of HDMA and/or ozone or filtered air for 6 mo. To detect structural changes in the BMZ, we measured immunoreactivity of collagen I. To detect functional changes in the BMZ, we measured perlecan and fibroblast growth factor-2 (FGF-2). We also measured components of the FGF-2 ternary signaling complex [fibroblast growth factor receptor-1 (FGFR-1) and syndecan-4]. The width of the BMZ was irregular in the ozone groups, suggesting atypical development of the BMZ. Perlecan was also absent from the BMZ. In the absence of perlecan, FGF-2 was not bound to the BMZ. However, FGF-2 immunoreactivity was present in basal cells, the lateral intercellular space (LIS), and attenuated fibroblasts. FGFR-1 immunoreactivity was downregulated, and syndecan-4 immunoreactivity was upregulated in the basal cells. This suggests that FGF-2 in basal cells and LIS may be bound to the syndecan-4. We conclude that ozone and HDMA plus ozone effected incorporation of perlecan into the BMZ, resulting in atypical development of the BMZ. These changes are associated with specific alterations in the regulation of FGF-2, FGFR-1, and syndecan-4 in the airway epithelial-mesenchymal trophic unit, which may be associated with the developmental problems of lungs associated with exposure to ozone.
Brown Norway (BN) rats develop a robust response to antigens in the lung, characterized by a large increase in allergen-specific immune function and pulmonary eosinophilia. The objective of this study was to investigate alternative models by determining whether other rat strains could be sensitized to house dust mite (HDM) antigen and whether the allergic disease process could be worsened with repeated allergen exposure. In general, BN rats sensitized by either subcutaneous or intratracheal routes exhibited increased pulmonary allergy compared with Sprague-Dawley (SD) and Lewis (L) rats. Multiple intratracheal allergen exposures incrementally increased HDM-specific immune function in BN rats but progressively decreased eosinophil recruitment and markers of lung injury. SD rats had more moderate responses, whereas L rats were relatively unresponsive. Because BN rats developed stronger clinical hallmarks of allergic asthma under various immunization regimes compared with SD and L rats, we conclude that the BN is the most appropriate strain for studying allergic asthma-like responses in rats. Phenotypic differences in response to HDM were associated with differences in the Th1/Th2 cytokine balance and antioxidant capacity.
BACKGROUND: Dermatophagoides pteronyssinus, Dermatophagoides siboney and Blomia tropicalis are the most important allergenic mites in Cuba. The aim of this study was to determine the degree of polysensitization and correlation of the skin prick test (SPT) reaction size to these mites in asthmatic patients. METHODS: A total of 232 adult patients with asthmatic symptoms caused by house dust and positive SPT to at least one mite were included. Standardized allergenic extracts were used in SPT. RESULTS: A total of 88.4% of patients were positive to D. siboney, 87.1% to D. pteronyssinus, and 68.1% to B. tropicalis. Sensitization to Dermatophagoides species was predominant, demonstrated by the fact that 31.9% of patients showed positive SPT to either D. siboney or D. pteronyssinus only, whereas only 5.6% was sensitized solely to B. tropicalis. Nevertheless, most patients (58.6%) were polysensitized to the 3 species. The mean wheal size produced by the different allergens in positive patients was similar (n.s. p > 0.05). Reaction size was strongly correlated (r = 0.71, p = 5.3 x 10-09) between D. siboney and D. pteronyssinus, whereas no significant correlation was found between D. pteronyssinus or D. siboney and B. tropicalis. CONCLUSIONS: The results of this study support the need to include the 3 allergens in diagnostic panels and for combined allergen-specific immunotherapy.
BACKGROUND: Esophagitis is an increasingly diagnosed disease. Patients with gastroesophagic reflux, dysphagia, vomiting or abdominal pain, with a torpid response to the treatment, could be suffering from it. MATERIAL AND METHODS: A 37 year-old male patient with background of gastroesophagic reflux and dysphagia for solids since 2002, self-limited diarrhea episodes and intolerance to alcoholic drinks due to epigastric pain. Skin prick tests, specific IgE, histamine release test and basophil activation test were carried out. RESULTS: Skin prick test to the usual allergens with negative result; prick-prick tests to egg white and yolk, milk and apple with positive result to egg white; total serum IgE within normal levels, specific IgE to egg white with positive result; histamine release test (HRT) and basophil activation test (BAT) with positive result to egg white and yolk. CONCLUSION: The patient was diagnosed eosinophilic esophagitis. The commercial food extracts have a great variability in their allergenic composition, which could result in false negative results in the prick test. Prick-prick with the natural food is a more sensitive technique than prick in the diagnosis of food allergy. There are other useful in vitro techniques, apart from specific IgE, in the diagnosis of food allergy. In our case, an exclusion diet of the involved food was more effective than other treatments for remission of the symptoms.
BACKGROUND: Chronic pharmacotherapy is recommended to patients with persistent moderate-severe (PM-S) allergic rhinitis (AR). The cost of pharmacotherapy is the main barrier to achieve symptoms control. AIMS OF THE STUDY: To determine the benefits of mite subcutaneous immunotherapy (SIT) in patients with PM-S AR not satisfied with chronic pharmacotherapy received free of charge. METHODS: Open study with seven (7) patients with PM-S AR not satisfied with chronic pharmacotherapy. Prior to enrollment patients had received monthly for more than five months and free of charge, optimal pharmacotherapy. We compared, off pharmacotherapy, symptoms and quality of life (QOL) before and during SIT. RESULTS: Mite SIT improved nasal symptoms, non nasal symptoms and QOL. Off pharmacotherapy patients reported adequate control of symptoms and were satisfied. CONCLUSIONS: Not all patients with PM-S AR are satisfied with chronic pharmacotherapy, even if medication is received free of charge. SIT control symptoms and satisfies patients with PM-S AR unsatisfied with free chronic pharmacotherapy.
BACKGROUND: The house dust mite Dermatophagoides farinae is the most common aeroallergen causing human allergic asthma. Previously, we demonstrated that a high-molecular-weight allergenic fraction (HM1), which was abundant in D. farinae extracts, induced a proliferative response of T cells from healthy donors. The induction was mediated through the activation of macrophages without MHC class II restriction. In this study, we investigate whether HM1 influences the development of airway inflammation in murine models of asthma. METHODS: BALB/c mice were injected twice intraperitoneally with D. farinae fecal extract (Dff) at an interval of 5 days. They were exposed daily to aerosolized antigen (group 1: Dff, group 2: HM1, group 3: HM1-depleted Dff and group 4: PBS) for 10 days. The effect of HM1 on their airway inflammation was evaluated by measuring acetylcholine-induced airway hyperresponsiveness and inflammatory cell infiltration in lung tissue. RESULTS: The inhalation of the whole fecal extract or the HM1 fraction induced airway hyperresponsiveness which was detectable after 24 h and was maintained for as long as 120 h. The inhalation of extract depleted of the HM1 fraction induced hyperresponsiveness measured at 24 h but this was not maintained for 120 h. Macrophage infiltration was significantly prolonged in mice inhaling the whole extract and the HM1 fraction compared to the HM1-depleted extract. CONCLUSION: The inhalation of the high-molecular-weight HM1 fraction of D. farinae prolonged airway hyperresponsiveness and macrophage inflammation in a mouse model of hypersensitivity. The results indicate that the HM1 fraction which can induce T cell proliferation through macrophage activation may play a role in the duration of airway responsiveness.
BACKGROUND: Mite allergens have been involved in airway sensitization and allergic diseases. Immunoassays for the identification and quantifiction of house dust mite (HDM) allergens are useful to improve the knowledge of regional mite fauna and the remediation of mite allergens in allergic diseases. The present study analyzed the association between levels of HDM allergen and results of mite identification or skin prick test (SPT) in two different areas of Bahia, Brazil. METHODS: Forty-two asthmatic subjects from a rural area (group I; n = 21) and a slum (group II; n = 21) were evaluated through SPT with HDM allergens and had dust samples collected at their homes for mite identification and allergen measurements. RESULTS: Positive SPT to Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis allergens were observed in 42.9, 38.0 and 42.9% subjects from group I and in 47.6, 19.0 and 33.3% subjects from group II, respectively. D. pteronyssinus and B. tropicalis were identified in approximately 76 and 50% of samples from both groups, respectively. D. farinae was identified in 38.0 and 9.5% of samples from groups I and II, respectively (p < 0.005). Der p 1, Der f 1 and Blo t 5 detection were associated with mite identification (p < 0.05). Association between HDM allergen levels over 2 microg/g of dust and positive SPT occurred only with D. pteronyssinus (p < 0.0001). CONCLUSIONS: D. pteronyssinus was the most prevalent mite species in this study followed by B. tropicalis and D. farinae. Immunoassays done to measure mite allergens were associated with mite-species identification. We conclude that these three mite species must be included on panels for the diagnosis of allergic airway diseases in subjects living in such regions.
BACKGROUND: It remains to be established which factors contribute to the occurrence of asthma in allergic individuals. We hypothesized that differences in the late allergic inflammatory reaction to allergen between asthmatic and non-asthmatic house dust mite-allergic individuals might contribute to the difference in the clinical presentation of allergy. AIM: To compare allergen-induced changes in parameters for cellular inflammation during the phase of the late allergic reaction in the skin and nose, in house dust mite-allergic individuals with or without asthma. MATERIAL AND METHODS: Nasal and dermal allergen challenges with house dust mite (Dermatophagoides pteronyssinus) extract were performed in 52 house dust mite-allergic individuals, of whom 26 had mild to moderate persistent asthma and 26 had perennial rhinitis without current or past asthmatic symptoms. Serial nasal lavage samples were analyzed for the presence of inflammatory cells (eosinophils and neutrophils) and soluble markers associated with cellular inflammation [interleukin-5 (IL-5), interleukin-8 (IL-8), eosinophil cationic protein (ECP) and myeloperoxidase (MPO)]. Macroscopic late phase skin reactions were studied after intracutaneous skin tests with house dust mite extract. RESULTS: Fixed dose nasal allergen provocation elicited a similar degree of immediate allergic reaction as judged by plasma protein exudation and histamine concentrations in asthma and non-asthmatic rhinitis. Subsequently, no differences between groups were found during the phase of the late allergic reaction (4-24 h) in inflammatory cell influx, plasma protein leakage, ECP or MPO. Likewise, there were no differences in levels of chemotactic cytokines IL-5 and IL-8. In agreement with the results of nasal challenge, the late skin reaction after dermal challenge with a fixed allergen dose and after an allergen dose 10,000 times above the skin threshold for an early skin reaction did not differ between the groups. CONCLUSION: House dust mite-allergic patients with or without asthma have very similar late allergic inflammatory reactions in the skin and in the nose after allergen challenge. Hence, it is unlikely that the occurrence of pulmonary symptoms in asthma is explained by a general tendency of asthmatics to have an enhanced late allergic cellular inflammatory response. Nasal and dermal allergen provocations are adequate models to study allergen-induced inflammation but probably lack the pivotal link which is essential for the development of asthma.
BACKGROUND: Sensitivity to the mite Blomia tropicalis is related to asthma in tropical climates, but correlates of sensitivity to B. tropicalis and its relationship to Dermatophagoides pteronyssinus sensitivity have not been widely examined in families with asthma. The main objective of this study was to determine prevalence and correlates of sensitivity to these mites in families with asthma and characteristics of persons sensitized to both. METHODS: Antibodies to major antigens (Blo t 5 and Der p 1) of these mites were measured by immunochemiluminescent assay in 481 members of 29 families from Barbados ascertained through two asthmatic siblings. RESULTS: Blo t 5 sensitivity was present in 261 subjects (46%) and was associated with younger age, higher total serum IgE level, and more than a three-fold increased prevalence of asthma (42 vs. 13%). Der p 1 sensitivity was less common (27%) and showed similar associations with age, IgE, and asthma. Of the 261 subjects sensitized to Blo t 5, 116 were also sensitized to Der p 1; they were younger, had higher total and Blo t 5 specific IgE levels, and had more than twice the asthma prevalence as those sensitized to Blo t 5 alone (59 vs. 29%). Der p 1 sensitivity without Blo t 5 sensitivity was uncommon; 90% of those sensitized to Der p 1 were also sensitized to Blo t 5. Geometric mean total IgE levels were lowest in the 207 participants without any mite sensitization (102 U/ml), intermediate in 158 sensitized to either Blo t 5 OR Der p 1 (609 U/ml), and highest in 116 sensitized to both (1,869 U/ml). CONCLUSIONS: Blo t 5 is the predominant sensitizing mite allergen in these Barbadian families with correlates similar to Der p 1. Concomitant sensitization to Der p 1 appears to identify a more reactive subgroup of individuals at a higher risk of asthma.
During 2 months of the pollen season, the acute and putative adjuvant effect of traffic-related air pollution on respiratory health was investigated in children sensitised to grass pollen or house dust mite (HDM). Respiratory complaints were objectified via measurement of exhaled NO and inflammatory mediators in nasal lavage (NAL). During the study children, skin prick negative (n = 31) or positive to grass pollen (n = 22), HDM (n = 34) or grass pollen + HDM (n = 32), kept a daily diary on respiratory symptoms, and NAL and exhaled air was sampled twice a week. The level of air pollutants and pollen was monitored continuously. Like children sensitised to HDM, those sensitised to pollen reported respiratory complaints (shortness of breath, itchy eyes or blocked nose) more frequently than non-sensitised children during (but not before) the pollen season; the respiratory complaints of sensitised children were independent of the pollen level. In addition, exposure to increased levels of PM(10) induces 'shortness of breath' in pollen- and HDM-sensitised children, whereas ozone induces a blocked nose in HDM-sensitised children. Combined exposure to PM(10) + pollen and O(3) + pollen induces a blocked nose in both HDM-sensitised children and children sensitised to pollen + HDM. Significant positive associations were found between eNO and the levels of NO(2), CO, PM(2.5) and pollen in both sensitised and non-sensitised children. At the start of the pollen season, the NAL concentration of eosinophils and ECP in pollen-sensitised children was increased compared to winter, but their levels were not further affected by increased exposure to pollen or air pollution. In conclusion, during the pollen season, sensitised children continuously report a high prevalence of respiratory complaints which coincides with increased levels of upper and lower airway inflammatory markers. No additional pro-inflammatory effect of air pollution was observed, which indicates that air pollution does not facilitate allergen-induced inflammatory responses.
BACKGROUND: Blomia tropicalis and Dermatophagoides pteronyssinus are important mite species in Tenerife, Canary Islands, Spain. Several studies have demonstrated a variable degree of allergenic cross-reactivity in vitro. However, only a few have addressed their allergenic cross-reactivity using challenge tests. OBJECTIVE: The objective of this study was to conduct conjunctival and bronchial challenge tests with B. tropicalis and D. pteronyssinus extracts in a group of 42 patients with allergic asthma and/or rhinoconjunctivitis sensitised to house dust mites (31 females, 11 males; mean age 21.7 +/- 7.02 years). METHODS: Prick tests using standardised extracts and specific IgE determinations using the CAP system were performed. Bronchial and/or conjunctival challenges were conducted using freeze-dried extracts of both mite species. A patient was considered sensitive to a mite species if she/he had a positive prick and/or CAP test result. A total of 32 conjunctival and 15 bronchial challenges were performed with both mite species. RESULTS: Prick tests were positive to B. tropicalis in 23 patients (54.7%) and to D. pteronyssinus in 41 (97.6%). One patient (2.4%) was exclusively sensitive to B. tropicalis. The CAP test was positive for B. tropicalis in 28 patients and for D. pteronyssinus in 41. Conjunctival challenges to B. tropicalis were positive in 20 patients (18 sensitised and 2 non-sensitised) and negative in 12 (5 sensitised and 7 non-sensitised patients). Conjunctival challenges with D. pteronyssinus were positive in all 31 D. pteronyssinus-sensitised patients who underwent conjunctival challenges. Bronchial challenges with B. tropicalis were positive in 9 sensitised patients and negative in 6 patients (2 sensitised and 4 non-sensitised). Bronchial challenges with D. pteronyssinus were positive in all patients except 1, who only reacted to B. tropicalis. CONCLUSIONS: Allergens of the mite species B. tropicalis induce positive conjunctival and bronchial challenges in B. tropicalis-sensitised individuals. Our results suggest that although there is a low to moderate degree of in vivo cross-reactivity between B. tropicalis and D. pteronyssinus, B. tropicalis seems to be a relevant source of allergens in areas where patients are exposed.
BACKGROUND: Although theophylline has long been used as a medication for bronchial asthma (BA), much remains to be elucidated about its action on Th2 cells, which play a critical role in the development of BA. OBJECTIVE: This study aimed to clarify the effect of theophylline on Th2 cells in an allergen-specific manner in children with BA. METHODS: Peripheral blood mononuclear cells (PBMCs) from 32 children with BA were stimulated with house dust mite (HDM) or a purified HDM allergen Der f 1 in the presence or absence of theophylline at a therapeutic concentration (5-20 microg/ml). The proliferation of lymphocytes and the secretion of IL-5 and IL-13 were measured to estimate the influence of theophylline. RESULTS: Theophylline at a concentration of 20 microg/ml significantly suppressed lymphocyte proliferation induced by 6-day culture with HDM or Der f 1. It also significantly reduced the production of IL-5 and IL-13 upon stimulation with HDM or Der f 1. Suppression of cytokine production and lymphocyte proliferation increased with concentrations of theopylline between 5 and 20 microg/ml. CONCLUSION: Theophylline suppresses the proliferation of lymphocytes and the production of proinflammatory Th2 cytokines, IL-5 and IL-13 induced by stimulation of PBMCs with HDM in children with BA.
BACKGROUND: House dust mite (HDM)-sensitive allergic rhinitis is a perennial rhinitis with persistent nasal inflammation. Currently, there are no reliable parameters to monitor the severity of perennial allergic rhinitis. The purpose of this study was to evaluate correlations between clinical and laboratory parameters in patients with HDM-sensitive allergic rhinitis. METHODS: We measured nasal symptoms, did the Dermatophagoides pteronyssinus (Der P) skin prick test (SPT), evaluated the Der P allergen nasal challenge threshold, and laboratory parameters [(1) inflammatory cell count from nasal mucosal scraping specimens: eosinophils and neutrophils and (2) immunocytochemistry: ICAM-1 expression on nasal epithelial cells] in 20 cases of HDM-sensitive allergic rhinitis and performed correlation tests between all parameters. RESULTS: The wheal diameter induced by Der P SPT was significantly correlated with the Der P allergen nasal challenge threshold (p = 0.001). The number of eosinophils from nasal mucosal scrapping specimens was correlated with the ICAM-1 expression on nasal epithelial cells (p = 0.039), the number of neutrophils from nasal mucosal scrapping specimens (p = 0.001), and nasal stuffiness (p = 0.037) but did not correlate with total nasal symptom scores. CONCLUSION: Clinical symptoms of HDM-sensitive allergic rhinitis showed a poor correlation with inflammatory parameters. The eosinophil count in nasal mucosa is correlated with ICAM-1 expression and more suitable than ICAM-1 levels to evaluate the severity of HDM-sensitive allergic rhinitis. This study also supports the role of the SPT in the diagnosis of nasal allergy to HDM.
BACKGROUND: Exposure and sensitization to indoor allergens have been associated with the development of asthma and other allergic diseases in many parts of the world. It is important to establish the degree of exposure, and to evaluate whether allergen control measures are effective in a particular area. METHODS: Concentrations of major allergens of mites, cockroach, cat and dog were measured in dust samples from homes of 24 mite-allergic patients living in Ribeirão Preto, Brazil. Allergen concentrations were quantitated by monoclonal antibody-based ELISA. Mite-impermeable mattress and pillow covers were applied to beds in the homes of 19 of the 24 patients, and group 1 mite allergen levels were measured 1 and 6 months following intervention. RESULTS: Patients were exposed to high concentrations of mite allergens in their homes. 87.5% of the homes presented concentrations of group 1 allergens >10 microg/g of dust in at least one site. Cockroach allergen concentrations were low in most samples. Dog allergen concentrations were significantly higher in homes with dogs as compared to those without dogs. Mean concentrations of cat allergen were 0.1 microg/g. Mite allergen concentrations in bedding samples dropped from 24 microg/g at baseline to 0.9 and 1.0 microg/g, respectively, 1 and 6 months following encasement of mattresses and pillows. CONCLUSIONS: Significant mite allergen reduction can be achieved in an area of high degree of exposure to mite allergens. Further studies evaluating the effect of this reduction on symptoms and airway inflammation will be necessary to establish the effectiveness of mite avoidance measures in our area.