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At least 199 records · Page 11Linked to original sources
PubMed1999

Effects of house dust mite avoidance measures on Der p 1 concentrations and clinical condition of mild adult house dust mite-allergic asthmatic patients, using no inhaled steroids.

BACKGROUND: Exposure to house dust mite (HDM) allergens often results in worsening of asthma. Therefore, avoidance of exposure to HDM allergens is often proposed. Unfortunately, the most effective and feasible avoidance strategy is still not completely assessed. Consequently, we investigated the effects of a combined HDM avoidance strategy on HDM allergen concentrations and clinical condition of allergic, mild asthmatic, patients using no inhaled steroids. METHODS: Asthmatic patients, allergic to HDM, using no inhaled corticosteroids, were randomly allocated to an active (n = 76) or a placebo allergen-avoidance group (n = 81). Avoidance measures consisted of applying Acarosan(R) (placebo: water) to the living room and bedroom floors, and the use of HDM-impermeable covers for mattresses and bedding (placebo: cotton covers for mattresses only). Effects on allergen concentrations (Der p 1), FEV1, bronchial hyperresponsiveness, peak flow parameters and asthma symptom scores were studied during 20 weeks and controlled for the allergic status of the patients. RESULTS: The active covers reduced Der p 1 concentrations to 9.4% (P = 0.0001), and were always significant lower than in the placebo group (P = 0.0002). Acarosan(R) resulted in slight but significant decreases (twofold, P = 0.0001), both on living room and bedroom floors, but concentrations were never significantly lower than the placebo group. Although the combined avoidance strategy resulted in a considerable reduction in allergen load in the active group, no differences were seen between the two groups in any of the clinical parameters during the follow-up period in this group of allergic asthmatics, using no inhaled corticosteroids. Corrections for the allergic status did not alter these results. CONCLUSIONS: The combined avoidance strategy was effective in reducing HDM allergen concentration. This was especially achieved by the allergen-impermeable covers, while the effects of Acarosan(R) were only marginal. However, this allergen reduction was not reflected in a convincing improvement in clinical condition in this group of mild allergic asthmatics, using no inhaled steroids. Perhaps, a longer follow-up period would have resulted in more pronounced effects.

Administration, Inhalation↗
PubMed1993

Molecular cloning of a house dust mite allergen with common antibody binding specificities with multiple components in mite extracts.

Plaque radio-immuno assay has been used to isolate an IgE-binding clone from a lambda gt11 library of Dermatophagoides pteronyssinus cDNA. The clone HD6 contained DNA encoding a 215 residue protein which contained a predicted 17 amino acid residue leader sequence, no cysteines and a single N-glycosylation site. The 198 residue mature protein would have a predicted MW of 22,177 D. No homologues were found in searches of the data banks. Sera from 14/38 allergic children reacted strongly with the polypeptide produced by the clone (37%). Skin tests showed reactivity in 16/30 (53%) allergic patients and 0/10 of controls. Affinity purification of rabbit antibodies with the clone showed that antibodies to the polypeptide had specificities to multiple products in mite extracts corresponding to components of Mr 29, 27 and 24 K by Western blotting. Absorption studies of IgE in allergic serum indicated further entities at 13 and 11.5 kD. It is proposed to name this allergen Der p VII.

Allergens↗
PubMed1989

Measurement of allergens associated with dust mite allergy. II. Concentrations of airborne mite allergens (Der I and Der II) in the house.

Assays of mite allergens (Der p I, Der f I and Der II) in the air of houses became feasible with the use of a low-noise air sampler and a sensitive radioimmunoassay described previously. The levels of the airborne allergens Der I (Der p I + Der f I) and Der II in the living room of 10 houses during usual domestic life were very low, 29.5 and 6.3 pg/m3, respectively, with a Der I: Der II ratio of 4.7:1. At the time of bedmaking, they greatly increased, about 1,000-fold, to 30,900 and 12,600 pg/m3, respectively, with a Der I: Der II ratio of 2.5:1. The amounts of Der I and Der II in the floor dust of the living room were 2,040 and 2,690 ng/g of fine dust, respectively, with a Der I: Der II ratio of 0.8:1. Der I seemed more prone to become airborne than Der II.

Air↗
PubMed2004

Clinical effectiveness of a mite allergen-impermeable bed-covering system in asthmatic mite-sensitive patients.

BACKGROUND: Exposure to allergens plays a role in the development of bronchial hyperresponsiveness and in the chronic inflammatory response seen in asthmatic patients. House dust mites (HDMs) are an important source of allergen. Reduction of these allergens might lead to better lung function and reduction of asthma symptoms. OBJECTIVE: The effect of HDM-impermeable covers on HDM allergen levels, peak flow values, and asthma symptoms were measured. Therefore a randomized clinical trial was carried out. METHODS: Fifty-two allergic asthmatic patients were randomly allocated to use the HDM-impermeable or placebo covers. During the study period, daily peak flow and asthma symptom scores were recorded. Dust samples were taken from the mattresses. RESULTS: We observed a significant reduction in HDM allergen levels on the mattresses after encasing them with HDM-impermeable covers (reduction of 87% of Der p 1 in micrograms per gram of dust; P <.001). Baseline symptoms were so low that no improvement could be established. Morning peak expiratory flow is significantly higher in the intervention group compared with that seen in the placebo group during the study period (beta=20.2; P <.01). CONCLUSIONS: HDM-impermeable covers significantly decreased the level of HDM allergens. Furthermore, morning peak flow was significantly increased during the intervention period. This study indicates that HDM allergen-avoidance measures might have beneficial effects on allergen reduction and asthma outcome.

Adult↗
PubMed2001

Evaluation of mite allergen-induced Th1 and Th2 cytokine secretion of peripheral blood mononuclear cells from atopic dermatitis patients: association between IL-13 and mite-specific IgE levels.

There have been several reports about Th1/Th2 imbalances in atopic dermatitis (AD), but there have been few precise investigations about the differences between Th1 and Th2 cytokine secretion patterns of peripheral blood mononuclear cells (PBMCs) in such patients. We cultured PBMCs, taken from AD patients and healthy subjects, with dust mite extract (DME) and measured subsequent immunoreactive interferon (IFN)-gamma (Th1 cytokine), interleukin (IL)-4, IL-5, and IL-13 (Th2 cytokines) levels in the supernatants by ELISA assays. There is a difference between IL-4 and IL-13 secretion patterns by DME-stimulated PBMCs in AD subjects; immunoreactive IL-4 levels were detectable maximally within 24-h cultures, while IL-13 levels increased time-dependently within 7-day cultures. IL-13 levels were significantly elevated in AD subjects compared to healthy subjects, while IFN-gamma levels did not significantly differ between the two groups. IL-13 levels were significantly higher in AD patients who had high levels (>100 U/ml) of Dermatophagoides pteronyssinus-specific IgE (Dp-IgE) than in those AD patients who had low levels (<10 U/ml) of Dp-IgE. Tacrolimus (FK-506), at a concentration of 10(-8) M, significantly inhibited DME-induced IL-13 production from PBMCs. These findings suggest that IL-13 produced by Th2 cells are involved in IgE overproduction in AD subjects.

Adult↗
PubMed2000

Association of HLA-DRB1(*)07 and DRB1(*)04 to citrus red mite (Panonychus citri) and house dust mite sensitive asthma.

BACKGROUND: Specific IgE responses to allergens provide useful models for evaluating the genetic factors that control human immune responses. A recent survey demonstrated that the citrus red mite (Panonychus citri, CRM) is the most important allergen in the development of asthma in citrus farmers. OBJECTIVE: The aim of this study was to evaluate whether susceptibility or resistance to CRM-induced asthma was associated with HLA-DRB1 gene. METHODS: DNAs were extracted from two groups of unrelated Korean adults living around citrus farms: (1) Ninety-one adults with CRM-sensitive asthma; and (2) 98 exposed, healthy nonatopic controls. Genotypes of HLA-DRB1 alleles were carried out using PCR-based methods. RESULTS: Allelic frequency of HLA-DRB1(*)07 was higher in the CRM-sensitive asthmatics compared to the controls (17.6% vs 4.1%, Pc = 0.01). Conversely, the frequency of DRB1*04 was lower in the CRM-sensitive asthmatics compared to the controls (19.8% vs 40.8%, Pc = 0.01). No significant difference was found in the distributions of the other HLA-DRB1 gene-encoded antigens between the two groups. CONCLUSION: HLA-DRB1 genes may be involved in the development of CRM-induced asthma. In addition, HLA-DR7 may increase, and DR4 decrease, the risk of developing the asthma in CRM-exposed adults.

Adult↗
PubMed2002

House dust mites and their allergens at selected locations in the homes of house dust mite-allergic patients.

BACKGROUND: Knowledge of the occurrence of house dust mites (HDM) and their allergens in domestic locations is important when planning intervention. OBJECTIVE: The aim of this study was to describe the distribution of HDMs and their allergens before intervention in multiple locations in the homes of newly diagnosed HDM-allergic patients with a known high Der 1 concentration in their mattress dust. METHODS: Dust was collected from ten locations in the homes of eight HDM-allergic patients. Dust was analysed for allergen content with ELISAs for Der f 1, Der p 1 and Der m 1; and HDM were counted. Total allergen concentrations ( micro g Der 1/g dust) were expressed as the sum of Der f 1, Der p 1 and Der m 1. RESULTS: On mattresses the median concentration was 86 micro g Der 1/g dust (range 30-288) and 188 mites/g dust (range 12-1910). Der 1 exceeded 10 micro g/g dust in mattresses (8/8), duvets/pillows (3/8), a bedroom carpet (1/1), a living room carpet (1/6), upholstered furniture (2/8) and a curtain (1/5). Uncarpeted floors, upholstered furniture, bookshelves and walls had significantly lower Der 1 concentration than the mattresses. The relative contribution of Der p 1, Der f 1 or Der m 1 to Der 1 was related to homes, rather than to the location. Der m 1 only occurred in minute amounts. CONCLUSION: For HDM intervention, our results indicate that priority should be given to the removal of allergens from mattresses, and in addition from carpets, duvets/pillows and upholstered furniture. Dust from walls, uncarpeted floors, bookshelves and curtains appear to contribute insignificantly to the domestic HDM allergen load.

Animals↗
PubMed2001

Identification of IgE-binding components of citrus red mite in sera of patients with citrus red mite-induced asthma.

BACKGROUND: Our previous investigations demonstrated that citrus red mite (CRM) antigen could cause IgE-mediated bronchoconstriction in exposed farmers working on citrus farms. OBJECTIVE: This study was performed to confirm IgE-binding components and major allergens within the CRM antigens. METHODS: Ten subjects who had been diagnosed as having CRM-induced asthma were enrolled. Serum-specific IgE antibodies to CRM antigens were measured by using an ELISA. To identify IgE-binding components and major allergens, SDS-PAGE, 2-dimensional PAGE, IgE-immunoblot analysis, and amino acid sequencing of major allergens were performed. RESULTS: All the asthmatic subjects had high specific IgE antibodies to CRMs. Twelve percent SDS-PAGE analysis showed more than 10 protein bands ranging from 6 to 64 kd. SDS-PAGE and IgE-immunoblot analysis with each individual serum showed 5 IgE-binding components (11, 24, 35, 40, and 64 kd), with 2 (24 and 35 kd) of them bound in more than 50% of the study subjects. Two-dimensional PAGE and IgE-immunoblot analysis demonstrated that the major allergen at 24 kd had 2 bands with different isoelectric points of 4.75 and 5.1. Thirty-five kilodaltons had one band with an isoelectric point of 4.75. All amino acid sequencing of the 2 major allergens was performed, which was not homologous with any previously characterized allergens. CONCLUSION: Five IgE-binding components and 2 major allergens (24 and 35 kd) were identified within the CRM antigen. The N-terminal amino acid sequence of the 2 major allergens (24 and 35 kd) was determined.

Adult↗
PubMed2006

Pilot investigation of a model for canine atopic dermatitis: environmental house dust mite challenge of high-IgE-producing beagles, mite hypersensitive dogs with atopic dermatitis and normal dogs.

Although canine atopic dermatitis (cAD) is common, few models are available. The aim of this study was to evaluate high-IgE beagles epicutaneously sensitized to house dust mite (HDM) as a possible model for cAD. Six high-IgE beagles were environmentally challenged with HDM using various doses and protocols. Similar challenge protocols were used in positive and negative control dogs: three dogs with naturally occurring cAD and positive intradermal skin test (IDT) to HDM and three normal dogs without history of skin disease and negative IDT to HDM. All high-IgE beagles and all atopic dogs developed severe cutaneous lesions and pruritus after challenge. Lesions were erythematous papules and macules in contact areas such as face, ears, ventral abdomen, groin, axillae and feet. They were first visible after 6 h and increased in severity over time. No normal dog developed pruritus or lesions. Biopsies of representative lesions in the high-IgE beagles were taken for histopathology and immunohistochemistry. There was superficial perivascular dermatitis with mononuclear infiltrates and spongiosis. Lymphocytes and eosinophils accumulated in small epidermal micro-abscesses with hyperplasia of epidermal IgE-bearing dendritic cells. These findings suggest that this colony of high-IgE beagles develops a dermatitis that clinically, histopathologically and immunologically resembles the naturally occurring canine disease. It is also concluded that this modality of challenge is not irritating to normal dogs but induces flare-ups in hypersensitive atopic dogs.

Animals↗
PubMed2002

A high-molecular-weight mite antigen (HM1) fraction aggravates airway hyperresponsiveness of allergic mice to house dusts and whole mite cultures.

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.

Air Pollution, Indoor↗