Thirty-one adult patients with asthma caused by house-dust mites (HDM) were included in this placebo-controlled, double-blind study to evaluate the efficacy and safety of specific immunotherapy (SIT) with biologically standardized extracts of HDM. The specific diagnosis was confirmed by skin prick tests, specific IgE, and bronchial provocation tests with HDM allergens. The patients were randomized to receive active treatment with extracts of either Dermatophagoides pteronyssinus (Dpt) or D. farinae (Dfa) (Alutard SQ, ALK, Denmark) or placebo injections. Twenty-three patients completed the study. After 1 year of treatment, we found a clinically important and significant reduction in both asthma medicine consumption (inhaled steroids 38% and beta 2-agonists 46%) and symptom score (57%) in the actively treated group, but not the placebo group. These findings were confirmed by a significant decrease in skin and bronchial sensitivity to HDM in the active group. Additionally, there was a significant difference in the patients' scores for effect in favor of the actively treated group. Total IgE and specific IgE to HDM showed no significant changes before and after treatment for either group. Spirometric lung-function measurements showed a significant increase in forced expiratory volume in 1 s (FEV1) from 85% before to 89% of predicted values after treatment for the actively treated group. Peak-flow measurements at home showed no significant changes during the study. It is concluded that allergen SIT is an effective treatment in adult patients suffering from asthma due to HDM.
BACKGROUND: Previous studies have shown a high prevalence of atopic diseases among school children in the community of Sør-Varanger. Moreover, animal dander followed by pollen and house dust mite, were the most common allergens in skin prick tests. OBJECTIVE: To assess the allergen content in homes (living-rooms and mattresses) and classrooms of children living in an arctic area at 70 degrees. The presence of allergens in homes and schools and their relationship to atopy was of particular interest. METHODS: Dust samples from 38 homes and seven schools in northern Norway were collected by vacuum cleaning. The presence of allergens of dog, birch, timothy, Cladosporium herbarum, codfish and hen egg-white was investigated by radio-allergosorbent test (RAST) inhibition and the presence of major allergens of cat Felis domesticus (Fel d I) and house dust mites (HDM) Dermatophagoides pteronyssinus (Der p I) and Dermatophagoides farinae (Der f I) by enzyme-linked immunosorbent assay (ELISA). RESULTS: Mattresses contained significantly more dust per unit area than living-rooms and classrooms. No statistically significant differences in allergen content for dog, birch, timothy. Cladosporium, codfish and hen egg-white were seen between HDM-sensitized and non-atopic children. Most dust samples contained dog allergens with the highest allergenic activity found in living-rooms of those keeping dogs. An increased level of Fel d I was detected in only one of 38 samples from living-rooms (this family kept a cat) and in 25 of 38 samples from mattresses with ranges from 24 to 84 ng/m2. The highest concentrations were found in mattresses of children keeping cats. Increased levels (> or = 25 ng/m2) of Der p I were found only in homes and virtually only in mattresses of HDM-sensitized children. An increased level of Der f I was found in only one case, i.e. in the mattress of an HDM-sensitized child where additionally Der p I and HDMs were demonstrated microscopically. When relating Der p I to HDM-sensitization an odds ratio of more than 16 (95% CI: 1.6-394.3) was found. All extracts from living-rooms included codfish allergens. Low RAST inhibition values were detected for hen egg-white. Cladosporium, birch and timothy pollen in most samples. Furthermore, the study demonstrated that dust from schools was relatively free of allergens. CONCLUSION: Previous findings indicating that the main allergen exposure problem in this geographical area is that of pet allergens were confirmed.
Allergy to indoor allergens can cause frequent and severe health problems in children. Because little is known about the content of allergens in the indoor environments in Norway, we wanted to assess the levels of cat, dog and mite allergens in schools and day-care centers in Oslo. Allergen levels in dust samples from 155 classrooms and 81 day-care units were measured using commercially available enzyme-linked immunosorbent assay (ELISA) kits. Additionally, we measured the levels of endotoxin in 31 day-care units, using the limulus amebocyte lysate test. Most of the dust samples contained detectable amounts of cat and dog allergens. In mattress and floor dust (day-care centers), and curtain and floor dust (schools) the median Fel d 1 levels were 0.17, 0.002, 0.02 and 0.079 microg/m2, while the median Can f 1 levels were 1.7, 0.03, 0.1 and 0.69 microg/m2, respectively. Levels of cat and dog allergens in school floor dust were associated with the number of pupils with animals at home. In contrast,
The aim of this study was to assess the distribution of allergen skin test reactivity in an unselected Danish population. A total of 793 subjects, aged 15-69 years, were invited, and 599 (75.5%) attended. The skin prick test was performed with standardized allergen extracts of high potency. Skin reactivity occurred in 28.4% of the subjects. The frequency of skin reactivity to the specific allergens ranged from 1.5% (Cladosporium) to 12.5% (Dermatophagoides pteronyssinus), and the frequencies of skin reactivity to the allergen groups (pollen, animal dander, house-dust mites, and molds) were 17.6%, 8.7%, 14.0%, and 3.2%, respectively. Young women appeared to reflect the average skin reactivity. When compared with young women, skin reactivity to animal dander was more probable in young men (odds ratio (OR) value = 2.6; 95% confidence interval (CI) of odds ratio value = 1.1-6.1). Current smokers were less likely than nonsmokers to be skin-reactive to pollen (OR = 0.4; 95% CI = 0.3-0.7). In conclusion, allergen skin test reactivity was common, and was related to sex, age, smoking history, and probably genetic predisposition.
Adults and children may have different reactions to inhalation exposures due to differences in target tissue doses following similar exposures, and/or different stages in lung growth and development. In the case of asthma and allergy both the developing immune system and initial encounters with common allergens contribute to this differential susceptibility. Asthma, the most common chronic childhood disease, has significant public health impacts and is characterized by chronic lung inflammation, reversible airflow obstruction, and immune sensitization to allergens. Animal studies described here suggest that air pollutants exacerbate asthma symptoms and may also play a role in disease induction. Changes characteristic of asthma were observed in rhesus monkeys sensitized to house dust mite antigen (HDMA) as infants and exposed repeatedly thereafter to ozone (O3) and HDMA. O3 exposure compromised airway growth and development and exacerbated the allergen response to favor intermittent airway obstruction and wheeze. In Brown Norway rats a variety of air pollutants enhanced sensitization to HDMA such that symptoms elicited in response to subsequent allergen challenge were more severe. Although useful for assessing air pollutants effects on initial sensitization, the rodent immune system is immature at birth relative to humans, making this model less useful for studying differential effects between adults and children. Because computational models available to address children's inhalation exposures are limited, default adjustments and their associated uncertainty will continue to be used in children's inhalation risk assessment. Because asthma is a complex (multiple genes, phenotypes, organ systems) disease, this area is ripe for systems biology approaches.
Biologic activity of Dermatophagoides siboney and Blomia tropicalis allergens in exposed and unexposed mite-allergic individuals. Effect of patient selection on the biologic standardization of mite extracts.
BACKGROUND: This study aimed to investigate the influence of patient selection criteria, i.e., mite-allergic individuals exposed and not exposed to Dermatophagoides siboney and Blomia tropicalis, on the biologic activity of mite extracts. Determination of the potency of mite extracts in vivo requires selection of patients with a clinical history of mite allergy. In Scandinavia, there are some anamnestic criteria for mite allergy, whereas in the tropics, where patients are continuously exposed to high levels of mites, selection of patients with mite allergy by clinical history is difficult. METHODS: A total of 210 Cuban asthmatics with continuous symptoms, and 43 Swedes with a clinical history of mite allergy were investigated. Skin prick tests were performed with D. siboney, D. pteronyssinus, D. farinae, B. tropicalis, Acarus siro, Lepidoglyphus destructor, and Tyrophagus putrescentiae extracts. For analysis of the biologic activity of mite extracts, Cuban patients were divided into four groups: 1) all patients skin-test-positive to mites 2) patients positive to mites, but not to other inhalant allergens 3) patients reacting most to the mite species analyzed 4) patients reactive only to mites and reacting most to the mite species analyzed. The biologic potency was calculated according to the Nordic Guidelines. RESULTS: Due to cross-reactivity between mites, Swedish mite-sensitive patients, with a clear clinical history of mite allergy, but not exposed to D. siboney and B. tropicalis, were more skin reactive to these mites than were Cubans. The estimated potency increased gradually to >200% in group 4. In group 1 Cubans, the reactivity to all mites but B. tropicalis was lower than that in mite-sensitive Swedes. CONCLUSIONS: According to the influence of patient selection criteria on the estimation of the potency of mite extracts, the determination of the biologic activity of allergenic extracts in subjects without a clear-cut clinical history should be replaced by new methods when available.
The presence of indoor allergens in Finnish homes was studied for the first time. Dust samples (n = 30) were collected by vacuuming a 1 m2 area from a living-room carpet in 30 apartments divided into three groups: homes with cats (n = 10), homes with dogs (n = 10), and homes without pets (n = 10). The levels of major cat (Fel d 1), dog (Can f 1), and house-dust-mite (Der p 1) allergens were analyzed by two-site ELISA methods. Der p 1 levels were below the detection limit in all dust samples. In the homes with cats or dogs, Fel 1 d and Can f 1 levels ranged from 147 to 2800 micrograms/g (geometric mean 296 micrograms/g), respectively, 567 micrograms/g), and from 86 to 1400 micrograms/g (geometric mean 296 micrograms/g), respectively, being slightly higher than those reported elsewhere. Low allergen levels, mainly below 3 micrograms/g were also detected in the homes without pets, indicating the transfer of allergens from place to place. However, in 25% of these samples, allergen levels exceeded the proposed threshold levels for cat or dog sensitization. The presence of pets was the most significant factor affecting cat and dog allergen levels in the house dust, and other factors, such as the amount of dust collected, residential time, and cleaning habits, had no or only a weak effect on allergen levels.
The house dust mite long has been studied for its potential role in atopic dermatitis. Its part in the pathogenesis of asthma and allergic rhinitis has been studied and is accepted. Testing for the dust mite allergen in this arena is performed with radioallergosorbent tests (RASTs) and prick testing. For several reasons, including the lack of a standardized testing tool, the difficulty in removing dust from the environment and the lack of association of dust and skin disease by patients, the role of the house dust mite in the pathogenesis of atopic dermatitis and skin disease has been questioned. Chemotechnique Diagnostics (Malmo, Sweden) now provides a standardized dust mite allergen in petrolatum in 2 concentrations. Dermatophagoides mix is a 50:50 mix of Dermatophagoides pteronyssinus and D. farinae at concentrations of 20% and 30%. The availability of a standardized patch test allergen for the house dust mite provides a better tool to investigate the role of this allergen as a contactant.
The present study revealed that 73% of surveyed apartments in Moscow whose residents included children with the atopic form of bronchial asthma and sensitization to Dermatophagoides pteronyssinus allergens were infested with the pyroglyphid mites D. pteronyssinus and D. farinae. The number of mites in the surveyed apartments varied between 0 and 154 mites/g of dust for D. pteronyssinus and between 0 and 162 mites/g of dust for D. farinae. The levels of mite allergens in these apartments ranged from 0.5 to 165.8 micrograms/g for Der p I and from 0.3 to 91.3 micrograms/g of dust for Der f I. The Der p I allergen was found to predominate, and its concentration in one-third of the apartments was more than 10-fold greater than that of Der f I. Correlation between the number of pyroglyphid mites and the concentration of group I allergens was established for both D. pteronyssinus (r = 0.4932; P
To investigate whether our hypothesis that cat and dog owners bring allergens to public areas in their clothes was true or not, we studied the levels of Fel d1, Can f1, Der p1 and Der f1 in dust from the clothes and classrooms of children in a Swedish school. We also investigated the levels of allergen in different areas in the four classrooms used by the children. Thirty-one children were selected in four classes, forming three groups: cat owners, dog owners and children without a cat or dog at home. Furthermore, a group of children with asthma was included. Cat and dog allergens were detected in all 57 samples from clothes and classrooms. Mite allergen Der f1 was detected in low concentrations in 6 out of 48 and Der p1 in 5 out of 46 samples investigated. The concentrations of Can f1 were higher than those of Fel d1 in samples from clothes (geometric mean: 2676 ng/g fine dust and 444 ng/g) and classrooms (Can f1: 1092 ng/g, Fel d1: 240 ng/g). The dog owners had significantly higher concentrations of Can f1 (8434 ng/g fine dust) in their clothes than cat owners (1629 ng/g, p