High mite-allergen exposure increases the risk of sensitization in atopic children and young adults

Molecular Signatures of Aeroallergen Sensitization in Pediatric Populations: A Comparative Study Across Spanish Cities

Spain exhibits significant climatic variability across its regions, ranging from the humid oceanic climate in the north to the Mediterranean and stepped climates in the southern and central areas. These climatic differences influence environmental allergen exposure, which may, in turn, affect allergic sensitization patterns in the pediatric population. Variations in temperature, humidity, and airborne allergen distribution, such as pollen, dust mites, animal epithelia, and mold, contribute to regional disparities in allergic responses among children. Understanding how climatic conditions shape allergen recognition patterns across different geographical areas is essential for improving allergy prevention and management strategies. This study aims to shed light on this issue by identifying sensitization patterns in a pediatric population of 236 patients (with 2 age groups analyzed: 6-10 and 11-15 years old) from different climatic regions of Spain. Skin tests with standard aeroallergens were performed, and specific IgE (sIgE) analysis by Allergy Explorer of Macroarray Diagnostic test (ALEX2) and Western blot. The results revealed different sensitization trends across patients from the eight cities analyzed (Barcelona, Granada, Lugo, Sagunto, Santiago de Compostela, Valencia, and Zaragoza).

Comparison of rush-subcutaneous and sublingual immunotherapy with house dust mite extract for pediatric allergic rhinitis: A prospective cohort study

BACKGROUND

We aimed to compare the effectiveness and safety of subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) with standardized house dust mite (HDM) extract for allergic rhinitis.

METHODS

Participants with allergic rhinitis selected their treatment between HDM SCIT or HDM SLIT, according to their wishes. We prospectively followed symptoms of allergic rhinitis using the allergic rhinitis symptom medication score (ARSMS), along with adverse reactions, during the dose escalation and maintenance phases for two years. We compared the outcomes between propensity score-matched groups to adjust the confounding factors.

RESULTS

After propensity score matching, 88 patients in the HDM SCIT (n = 44) and HDM SLIT groups (n = 44) remained for analysis. The HDM SCIT group showed significantly earlier effectiveness than the HDM SLIT group (median time to decrease in ARSMS [≥2 points]: 5.5 vs. 18.0 months, p < 0.001). The incidence of systemic reactions was not significantly different between the two groups in the dose escalation phase (68.2% vs. 56.8%, p = 0.379). In the maintenance phase, the incidence of systemic reactions was higher in the HDM SCIT group than in the HDM SLIT group (18.2% vs. 0%, p < 0.006). All 44 patients in the HDM SCIT group completed two years of treatment, while nine patients in the HDM SLIT group discontinued treatment.

CONCLUSIONS

The HDM SCIT group showed an earlier onset of therapeutic effect and a lower discontinuation rate than the HDM SLIT group, although more severe systemic reactions were observed during the maintenance phase.

The impact of poor housing and indoor air quality on respiratory health in children

It is becoming increasingly apparent that poor housing quality affects indoor air quality, significantly impacting on respiratory health in children and young people. Exposure to damp and/or mould in the home, cold homes and the presence of pests and pollutants all have a significant detrimental impact on child respiratory health. There is a complex relationship between features of poor-quality housing, such as being in a state of disrepair, poor ventilation, overcrowding and being cold, that favour an environment resulting in poor indoor air quality. Children living in rented (private or public) housing are more likely to come from lower-income backgrounds and are most at risk of living in substandard housing posing a serious threat to respiratory health. Children have the right to safe and adequate housing, and research has shown that either rehousing or making modifications to poor-quality housing to improve indoor air quality results in improved respiratory health. Urgent action is needed to address this threat to health. All stakeholders should understand the relationship between poor-quality housing and respiratory health in children and act, working with families, to redress this modifiable risk factor.

Educational aims

The reader should understand how housing quality and indoor air quality affect respiratory health in children.The reader should understand which children are at most risk of living in poor-quality housing.The reader should understand what policy recommendations have been made and what actions need to be undertaken to improve housing quality and respiratory health in children and young people.

Exposure to House Dust Mite Allergen and Endotoxin in Early Life and Sensitization and Allergic Rhinitis: The JECS

The association between endotoxin and allergic rhinitis (AR) is not conclusive. The aim of this study was to determine the association between endotoxin and house dust mite (HDM) allergens in dust, and HDM sensitization and AR among Japanese infants. This study included 4188 participants in the Sub-Cohort Study of the Japan Environment and Children's Study. Dust was collected from children's mattresses at age 18 months and endotoxin and HDM allergen levels were measured. A logistic regression model was used to analyze the association between endotoxin or HDM allergen and the sensitization to HDM (specific-IgE) at age 2 and AR at age 3. The median (interquartile range) endotoxin level was 375.1(186.9-826.5) EU/m² and the Der 1 (Der p 1 + Der f 1) level was 51.2 (14.8-168.6) ng/m². There were significant positive associations between endotoxin and HDM sensitization (Der f 1, adjusted odds ratio [aOR] quartile [Q] 4 vs. Q1, 1.44, 95% CI, 1.04-2.00; Der p 1, aOR Q4 vs. Q1, 1.56, 95% CI, 1.12-2.16). There were also significant positive associations between Der 1 exposure and HDM sensitization (Der f 1, aOR Q3 vs. Q1, 1.75, 95% CI, 1.26-2.44; aOR Q4 vs. Q1, 2.98, 95% CI, 2.15-4.13; Der p 1, aOR Q3 vs. Q1, 1.91, 95% CI, 1.37-2.66; aOR Q4 vs. Q1, 2.91, 95% CI, 2.09-4.05). There were, however, no associations between endotoxin or Der 1 and AR. In the population residing mostly in non-farming settings, both endotoxin and HDM allergens in dust were associated with an increased risk of HDM allergen sensitization, but not with AR.

The links between allergen exposure and sensitization in children and adolescents: an overview for the clinician

INTRODUCTION

The links between allergen exposure and sensitization are complex and depend not only on the type of allergen but on various genetic and environmental factors.

AREAS COVERED

This review discusses the link between allergen exposure and atopic sensitization for different types of allergens and the factors that mediate or affect this link. For the purposes of this review search of PubMed was undertaken to identify English language articles using the terms 'sensitization' and 'allergen exposure' and 'children/or adolescents.'

EXPERT OPINION

Regarding food sensitization, the available data for peanuts and eggs suggest that there is a window period between 4 and 6 months of age when the introduction of these foods may limit sensitization and clinically overt allergy to the respective foods. As far as it concerns aeroallergens, it seems that there is a complex and variable relationship between mite exposure and specific sensitization especially if the exposure occurs early in life. Early exposure to dog allergens does not seem to be associated with specific sensitization; regarding cats, the results are still inconsistent. Several factors may mediate the relationship between early exposure to allergens and the development of sensitization or clinical allergy.

Comparison of house dust mite sensitization profiles in allergic adults from Canada, Europe, South Africa and USA

BACKGROUND

Sensitization to house dust mite (HDM) is a leading cause of allergic rhinitis and asthma. Despite more than 30 HDM-derived allergens having been identified to date, specific therapeutic approaches do not yet take into account the local sensitization profiles of patients. This study aimed to identify patterns of HDM sensitization in HDM-allergic adults living in distinct geographic areas, to inform the development of targeted diagnostic and therapeutic tools.

METHODS

Serum samples from 685 HDM-allergic subjects from Canada, Europe, South Africa, and the USA were tested for levels of IgE specific for 17 micro-arrayed HDM allergens by ImmunoCAP Immuno Solid-phase Allergen Chip (ISAC) technology.

RESULTS

The results confirmed significant geographical variability in sensitization patterns and levels of IgE. In all areas, the major sensitizers were the group 1 and group 2 allergens and Der p 23. Der p 23 was a frequent sensitizer: 64% of the subjects had IgE specific for Der p 23, and 2.3% were monosensitized to it. In South Africa, Der p 23 was the dominant HDM allergen (86% prevalence) and Der p 7 achieved major allergen status (56%). IgE sensitization to HDM was influenced by asthmatic status, levels of allergen exposure, age, race-ethnicity and smoking status, but not by BMI.

CONCLUSION

Sensitization profiles to HDM allergens differ considerably among distinct geographic areas, with Der p 7 and Der p 23 being major sensitizers in South Africa. Such heterogeneity should be taken into account in the diagnosis and treatment of HDM-allergic patients.

Repeated immunosensing by a dithiobis(succinimidyl propionate)-modified SAW device

The possibility of dithiobis(succinimidyl propionate) (DSP) for repeated immunoassay with a surface acoustic wave (SAW) immunosensor was explored. In the sensor, DSP was used to modify a gold-coated quartz sensing area of a SAW device by forming a self-assembled monolayer on the gold surface. In a model sandwich assay using mouse (mIgG) and anti-mouse (a-mIgG) antibodies, the primary antibody, mIgG, firstly reacted with N-hydroxysuccinimide ester groups of DSP and was immobilized on the SAW device to fabricate the SAW immunosensor. Optimization of adsorption time of mIgG revealed that both degrees of adsorption and immobilization of mIgG reached a saturation at 30 min although the immobilization was more dependent on the adsorption time. Through characterization of the DSP-modified SAW immunosensor, a high selectivity, with which no sensor output was observed from various kinds of secondary antibodies except for a-mIgG, along with 8-fold shorter measurement time (15 min) than that of enzyme-linked immunosorbent assay were obtained. Furthermore, 10 repeated measurement of a-mIgG demonstrated a high reproducibility of the sensor output (coefficient of variation of 7.0%). These validate the utility of DSP in the SAW immunosensor for rapid and repeated measurement of antigens.

Cross-reactivity of sIgE to mite and shrimp induced allergies in different age groups and clinical profiles of shrimp sIgE in vegetarians

The sensitization to house dust mites (HDMs) and shrimps affects the development of hypersensitivity with an increase in age. Due to the cross-reactivity between shellfish and HDMs, HDMs were considered as the primary sensitizer for shellfish allergy. Thus, vegetarians might be sensitized to shrimp through the inadvertent inhalation of HDMs. Therefore, we assessed the prevalence of shrimp or mite allergy among different age groups and vegetarians. The serum specific-IgE (sIgE) level of HDMs and shrimp in 60 children/adolescence (un-adults), 30 adults, 30 elderly, and four vegetarian adults patients were measured. The sera with sIgE levels greater than 3.5 kUA/L were cross-reactivity examined. We found that HDMs induced higher sIgE than shrimp in un-adults. In contrast, shrimp-induced sIgE was higher in the adults and elderly patients. Moreover, adults were more frequently sensitized to shrimp and mite at the same time compared with the un-adult or elderly groups. The mite-Der p 10 not only displayed high cross-reactivity to the shrimp-Pen a 1 in all age groups and vegetarians but functioned as the major allergen to sensitize un-adults. Overall, the level of mite or shrimp sIgE is influenced by alterations in age, and vegetarians are at risk of shrimp sensitization via cross-reactivity between shrimp and mite.

Blo t 2: Group 2 allergen from the dust mite Blomia tropicalis

Blomia tropicalis has been recognized as a cause of allergic diseases in the tropical and subtropical regions. Here we report the immuno-characterization of its group 2 allergen, Blo t 2. Allergen Blo t 2 was amplified from the cDNA of B. tropicalis using degenerate primers, expressed in Escherichia coli as a recombinant protein and purified to homogeneity. The mature protein of Blo t 2 was 126 amino acids long with 52% sequence identity to Der p 2 and apparent molecular mass of 15 kDa. Circular dichroism spectroscopy showed that Blo t 2 is mainly a beta-sheeted protein. We confirmed the presence of three disulfide bonds in recombinant (r) Blo t 2 protein using electrospray mass spectrometry. Thirty-four percent of dust-mite allergic individuals from the Singapore showed specific IgE binding to rBlo t 2 as tested using immuno dot-blots. IgE-cross reactivity assays showed that Blo t 2 had between 20-50% of unique IgE-epitopes compared to Der p 2. IgE binding of native and recombinant forms of Blo t 2 were highly concordant (r2 = 0.77, p < 0.0001) to rBlo t 2. Dose-dependent in vitro histamine was observed when rBlo t 2 was incubated with whole blood of Blo t 2 sensitized individuals, demonstrating that it is a functional allergen. Nine naturally occurring isoforms of Blo t 2 were identified in this study, each having between 1-3 amino acid variations compared to the reference clone. Blo t 2 is a clinically relevant allergen of B. tropicalis as it has unique IgE epitopes compared to major group 2 allergens from Dermatophagoides spp.

Indoor allergen levels in settled airborne dust are higher in day-care centers than at home

BACKGROUND

Early-life sensitization to indoor allergens predicts asthma development. The aim of this study was to compare allergen concentrations in day-care centers (DCC) with those in private homes.

METHODS

Settled airborne dust was collected 4 times a year from 20 German DCC (620 samples) and from the homes of children and day-care workers (602 samples) using electrostatic dust collectors (EDC). The samples were analyzed with fluorescence enzyme immunoassays recognizing domestic mite allergens (DM), Fel d 1, Can f 1, and Mus m 1. Pet allergen thresholds that discriminate samples from homes with cats or dogs from those without were calculated using receiver-operating characteristics. Influences on allergen levels were analyzed using multilevel models.

RESULTS

Allergen loads were on average higher in DCC than in homes. In DCC, 96% of the samples were positive for DM, 95% for Can f 1, 90% for Fel d 1, and 83% for Mus m 1. In homes, 84% contained DM, 48.5% Can f 1, 33% Fel d 1, and 43% Mus m 1. The threshold level for homes with dogs was 75 ng/m² Can f 1 (96.8% sensitivity, 96% specificity), and the threshold level for homes with cats was 46 ng/m² Fel d 1 (92% sensitivity, 94.9% specificity). In DCC, Can f 1 and Fel d 1 loads were higher than these thresholds in 37% and 54% of the samples, respectively. Allergen levels were significantly influenced by the season and room type; however, carpets on floors had no influence.

CONCLUSIONS

Mite, mouse, cat, and dog allergens were mostly higher in DCC than in homes. Exposure to dog and cat allergens in DCC often reached levels of households with pets.

The relationships among Dermatophagoides pteronyssinus exposure, exhaled nitric oxide, and exhaled breath condensate pH levels in atopic asthmatic children

This study examined seasonal changes in indoor Dermatophagoides pteronyssinus 1 (Der p 1)/Blattella germanica 1 (Bla g 1) antigen concentrations in the homes of atopic asthmatic and atopic nonasthmatic children. Possible associations between environmental allergen exposure and levels of exhaled breath indices were also evaluated.A total of 38 atopic children were recruited for this cross-sectional study: 22 were asthmatic and 16 were nonasthmatic. Home visits were conducted for indoor air and dust sampling each season. Exhaled nitric oxide (eNO)/spirometric measurements were taken and exhaled breath condensate (EBC) was collected after sampling of the domestic environment.The highest Der p 1 concentrations were on the top of mattresses in the homes of recruited children. The floors of kitchens and living rooms had the highest Bla g 1 concentrations in the homes of atopic asthmatic children. A positive correlation was found between Der p 1 exposure of mattress, bedroom floor, and living room floor and eNO levels in the atopic asthmatic children. The Der p 1 concentrations on the surfaces of mattress and bedroom floor were positively related to high eNO levels in the atopic asthmatic children after adjusting for season. No association was found between Der p 1 exposure and EBC pH values in the recruited children.A positive correlation was found between Der p 1 exposure and high eNO levels in atopic asthmatic children, especially in Der p 1 exposure of mattress and bedroom floor.

Allergen quantification in surface dust samples from German day care centers

Indoor allergens are among the main causes of allergic rhinitis and asthma. Allergen exposure is not limited to private homes. Mite, cat, and dog allergens were measured in day care centers to determine whether these concentrations detected might exert significant influence on human health. In 20 day care centers across North Rhine-Westphalia, Germany, the surfaces of 171 rooms were vacuumed 4 times a year to collect dust (1340 samples in total). In all samples, domestic mite antigens (DM) and the main allergens of cats (Fel d 1) and dogs (Can f 1) were quantified using enzyme immunoassays. Provisional threshold limits (PTL) for increased risks of sensitization and allergic symptoms were estimated according to published values and conversion factors. The influence of room characteristics on allergen concentrations was analyzed in mixed linear models, also considering values below the limit of detection (LOD). Nearly all samples contained allergens (99% DM, 96% Fel d 1, and 96% Can f 1). The concentrations rarely exceeded levels that were previously found to induce symptoms in home environments, but were frequently higher than estimates for enhanced sensitization risk (13% DM, 43% Fel d 1, and 27% Can f 1). Upholstered furnishings had the highest dust and allergen loads, followed by carpets and smooth floors. Allergen concentrations on different surface types that were sampled in the same room at the same time were significantly correlated and analyzed in separate models. The highest DM concentrations were present in bedrooms and in autumn. Further, DM loads on floors decreased significantly in rooms that were renovated within the last 5 years. If there were no records that furnishings were vacuumed, there were then significantly higher Can f 1 loads. Sweeping floors elevated DM and cat allergen concentrations. In addition to mite allergens, cat and dog allergens were detected in nearly all samples from day care centers. Overall, the present results indicate that allergen concentrations may be reduced by renovation and appropriate cleaning procedures.

Asthma and Wheeze Prevalence among Nursing Professionals in Western Japan: A Cross-Sectional Study

Although adult asthma is attributable to occupational factors, few reports are available on asthma prevalence among health care workers in Japan. The objective of this study was to estimate the prevalence of asthma and wheeze among Japanese nursing professionals. A cross-sectional study was conducted by postal survey using a translated version of the European Community Respiratory Health Survey questionnaire from April to June 2013. The analysis included 4634 nursing professionals (257 men and 4377 women) and the overall response rate was 84.8%. The prevalence of current asthma and wheeze were 10.7% (95% confidence interval (CI), 9.9%-11.7%) and 15.6% (95% CI, 14.5%-16.6%), respectively. More than one year of work experience as a nursing professional and more than one year of experience with bed-making tasks were associated with odds ratios (ORs) of 1.95 (95% CI, 1.12-3.39) and 1.64 (95% CI, 1.15-2.23) for wheeze, respectively. Current smoking was significantly associated with the presence of wheeze, with ORs of 2.27 for men (95% CI, 1.11-4.64) and 2.01 for women (95% CI, 1.54-2.64). Among female nurses, latex allergy was associated with wheeze (OR, 1.87; 95% CI, 1.56-2.23), as was body mass index ≥30 (OR, 2.76; 95% CI, 1.65-4.62). This study has provided the prevalence of asthma and wheeze among Japanese nursing professionals. Employment period, bed-making tasks, latex allergy, obesity, and smoking may be risk factors for prevalent wheeze among nursing professionals.

Studies on the Occurrence, Identification and Control of House Dust Mites at Rural Houses of Shebin El-Kom Locality, Egypt

The present study was conducted at Elkom Elakhdar village, Shebin El-Kom, Menoufia Governorate along 2012 year seasons, to calculate and identify the species composition and the occurrence frequency of the extracted dust mites collected from three building ages at rural houses, as well as to determine the toxicity limits of different concentrations of three plant essential oils against two species of the family Pyroglyphidae the main causal of allergy to humans. The obtained results revealed that there were eleven mite species belong to five families (Pyroglyphidae, Chortoglyphidae, Glycyphagidae, Acaridae and Cheyletidae). Of the total collected mites (5276) the highest dominant percentage species was the dust mites: Dermatophagoides farinae (66.1%), followed by D. pteronyssinus (23.3%), while the percentages of the rest species: Chortoglyphus arcuatus, Lepidoglyphus destructor, Glycyphagus domesticus, Gohieria fusca, Tyrophagusputrescentiae, Caloglyphus sp, Cheyletus malaccensis, Blomia sp. and Acarus siro were ranged between 0.16-2.0%. Regarding to the effect of temperature degrees on mite population, high degrees more than 25 degrees C at summer season, decreased the numbers of D. farinae and D. pteronyssinus. Toxicological tests of the three plant essential oils against adult stages of D. farinae and D. pteronyssinus showed that lemon grass oil gave the highest toxicity effect, in comparison with geranium and thyme oils, where mortality percentages were approximately around 100% at 800 ppm concentration on both species. The LC50 of lemon grass were 228.992 and 293.615 ppm against the two species, respectively. From the results of the research, it could be recommend that it is preferable to apply control operation during summer season where the mite population density is the least, moreover, the botanical oil extracts effectively controlled the parasitic dust mites, D. farinae and D. pteronyssinus and can be used in the biological control programs, as well as, it can play effective role in the integrated management programs.

Early-life house dust mite allergens, childhood mite sensitization, and respiratory outcomes

BACKGROUND

Exposure to indoor allergens during early life may play a role in the development of the immune system and inception of asthma.

OBJECTIVE

To describe the house dust mite (HDM) allergen concentrations in bedroom dust during early life and to evaluate its associations with HDM sensitization, wheezing, and asthma, from birth to school age, in 5 geographically spread European birth cohorts.

METHODS

We included 4334 children from INMA-Menorca (Spain), BAMSE (Sweden), LISAplus and MAS (Germany), and PIAMA-NHS (the Netherlands). Dust samples were collected from bedrooms during early life and analyzed for Dermatophagoides pteronyssinus (Der p1) and Dermatophagoides farinae (Der f1). HDM concentrations were divided into four categories. Sensitization was determined by specific IgE. Wheezing and asthma information up to 8/10 years was collected through questionnaires. We performed mixed-effects logistic regression models and expressed associations as odds ratios with 95% confidence intervals.

RESULTS

House dust mite concentrations varied across cohorts. Mean allergen concentrations were highest in INMA-Menorca (geometric mean (GM) Der p1 = 3.3 μg/g) and LISAplus (GM Der f1 = 2.1 μg/g) and lowest in BAMSE (GM Der p1 = 0.1 μg/g, Der f1 = 0.3 μg/g). Moderate and high HDM concentrations were significantly (P-values < 0.05) associated with 50-90% higher prevalence of HDM sensitization. No significant associations were observed with respiratory outcomes.

CONCLUSION

Our study based on geographically spread regions, a large sample size, and a wide range of allergen concentration shows that HDM allergen concentrations vary across regions and that exposure during early life plays a role in the development of allergic sensitization but not in the development of respiratory outcomes.

Assessing the allergenic potential of molds found in water-damaged homes in a mouse model

Damp/moldy indoor environments, which have resulted from flooding events and may increase as a result of climate change, have been associated with asthma exacerbation. Certain molds found in significantly higher or lower concentrations in asthmatics' homes compared to control homes have been categorized as Group 1 (G1) and Group 2 (G2) molds, respectively. We have compared the allergic potential of selected G1/G2 molds to house dust mite (HDM) in a mouse model. BALB/c mice were exposed to mold (0-80 µg) or HDM (20 µg) extract by intratracheal aspiration either 4X over 4 weeks (allergenicity) or 1X (non-specific responses). Airflow limitation (methacholine challenge) was measured (Day 1) and serum and bronchoalveolar lavage fluid were collected (Day 2) after the final exposure. The G1 molds induced low-to-moderate responses and required higher doses to achieve antigen-specific IgE results similar to those induced by HDM. Compared to HDM responses, the G2 mold in this study required lower doses to induce a similar response. Acute exposure responses suggest some molds may exacerbate asthmatic responses. These studies demonstrate the differing capacities of molds to induce responses associated with allergic asthma, including differences in the threshold dose for allergy induction. Therefore, molds must be evaluated individually for allergic/asthmatic potential. These studies along with our previous studies with G1 (Stachybotrys chartarum)/G2 (Penicillium chrysogenum) molds suggest that the G1/G2 categorization is not indicative of allergic potential but they do not preclude this categorization's utility in determining unhealthy building dampness.

Role of adrenocorticotropic hormone in the modulation of pollinosis induced by pollen antigens

BACKGROUND

A mild restraint stressor suppressed an increase in the levels of Th2-dependent cytokines and IgE, thereby reducing the symptoms of pollinosis. In the present study, to clarify the mechanism of action of adrenocorticotropic hormone (ACTH) in improving the symptoms of pollinosis, we studied the effects of ACTH on the plasma level of histamine, mast cell number in nasal-associated lymphoid tissue (NALT) and the T cell differentiation in splenocytes.

METHODS

The role of ACTH in the development of pollen antigen-induced pollinosis was studied in mice. Allergic symptoms and parameters were measured on day 17 after sensitization. To investigate the effects of ACTH on T cell differentiation, we stimulated splenocytes obtained from control mice with ACTH and CD3/CD28 in vitro, and measured the cytokine production in the culture supernatant.

RESULTS

The plasma levels of IL-10, IgE and histamine and mast cell number in NALT were increased in the sensitized animals in association with a concomitant increase in the incidence of sneezing and nasal rubbing. The intraperitoneal administration of ACTH decreased the IL-10, IgE and histamine levels in the plasma and mast cell number in NALT, while increasing the IFN-γ level and suppressing the incidence of nasal rubbing. Furthermore, the production of IFN-γ increased, while the IL-4 level was suppressed after 2 days in culture.

CONCLUSIONS

The present findings showed that ACTH directly affects T cell differentiation and promotes Th1-type reactions. The regulation of the Th1/Th2 balance by ACTH may result in a decrease in the pathological features of pollinosis.

Respiratory allergy caused by house dust mites: What do we really know?

The house dust mite (HDM) is a major perennial allergen source and a significant cause of allergic rhinitis and allergic asthma. However, awareness of the condition remains generally low. This review assesses the links between exposure to HDM, development of the allergic response, and pathologic consequences in patients with respiratory allergic diseases. We investigate the epidemiology of HDM allergy to explore the interaction between mites and human subjects at the population, individual, and molecular levels. Core and recent publications were identified by using "house dust mite" as a key search term to evaluate the current knowledge of HDM epidemiology and pathophysiology. Prevalence data for HDM allergen sensitization vary from 65 to 130 million persons in the general population worldwide to as many as 50% among asthmatic patients. Heterogeneity of populations, terminology, and end points in the literature confound estimates, indicating the need for greater standardization in epidemiologic research. Exposure to allergens depends on multiple ecological strata, including climate and mite microhabitats within the domestic environment, with the latter providing opportunity for intervention measures to reduce allergen load. Inhaled mite aeroallergens are unusually virulent: they are able to activate both the adaptive and innate immune responses, potentially offering new avenues for intervention. The role of HDM allergens is crucial in the development of allergic rhinitis and asthma, but the translation of silent sensitization into symptomatic disease is still incompletely understood. Improved understanding of HDMs, their allergens, and their microhabitats will enable development of more effective outcomes for patients with HDM allergy.

The relationship between pollen count levels and prevalence of Japanese cedar pollinosis in Northeast Japan

BACKGROUND

The prevalence of Japanese cedar (JC) pollinosis in Japanese children is increasing. However, few studies have reported the relationship between pollen count levels and the prevalence of pollinosis. To evaluate the relationship between JC pollen count levels and the prevalence of pollinosis in children, we investigated the sensitization and development of symptoms for JC pollen in two areas of Akita in northeast Japan with contrasting levels of exposure to JC pollen.

METHODS

The study population consisted of 339 elementary school students (10-11 years of age) from the coastal and mountainous areas of Akita in 2005-2006. A questionnaire about symptoms of allergic rhinitis was filled out by the students' parents. A blood sample was taken to determine specific IgE antibodies against five common aeroallergens.

RESULTS

The mean pollen count in the mountainous areas was two times higher than that in the coastal areas in 1996-2006. The prevalence rates of nasal allergy symptoms and sensitization for mites were almost the same in both areas. On the other hand, the rates of nasal allergy symptoms and sensitization for JC pollen were significantly higher in the mountainous areas than in the coastal areas. The rate of the development of symptoms among children sensitized for JC pollen was almost the same in both areas.

CONCLUSIONS

These results suggest that pollen count levels may correlate with the rate of sensitization for JC pollinosis, but may not affect the rate of onset among sensitized children in northeast Japan.

Association between latitude and allergic diseases: a longitudinal study from childhood to middle-age

BACKGROUND

Worldwide variations in allergy prevalence suggest that geographic factors may contribute to asthma. Ecologic studies have suggested that latitude, a marker of UV-B exposure and allergen exposures, may be related to clinical allergies.

OBJECTIVE

To examine the relationship between latitude or UV-B based on self-reported geolocation and allergic sensitization and disease prevalence in Australia.

METHODS

The Tasmanian Longitudinal Health Study is a population-based study of respiratory disease spanning childhood to adulthood. The most recent follow-up included a postal survey of 5,729 participants and a clinical substudy of 1,396 participants. Participants' residential addresses were coded for latitude and linked with the UV-B data from satellite-based observations of atmospheric ozone. Multivariable logistic regression analyses were performed to estimate the associations between latitude or UV-B and allergic diseases.

RESULTS

Most northerly latitude, that is, latitude closest to the Equator, and high current UV-B exposure were associated with increased odds of hay fever, food allergy, and skin sensitization to house dust mites and molds. More northerly latitude and higher UV-B exposure were associated with increased odds of current asthma among atopic individuals contrasting with a reduced odds of current asthma among nonatopic individuals.

CONCLUSION

This is the first study, to our knowledge, to demonstrate a differential effect of atopic status on the relationship between latitude and current asthma. Our study demonstrates in a genetically and culturally similar group of individuals that geographic factors may a play role in the development of allergic disease.

Allergic Responses Induced by a Fungal Biopesticide Metarhizium anisopliae and House Dust Mite Are Compared in a Mouse Model

Biopesticides can be effective in controlling their target pest. However, research regarding allergenicity and asthma development is limited. We compared the ability of fungal biopesticide Metarhizium anisopliae (MACA) and house dust mite (HDM) extracts to induce allergic responses in BALB/c mice. The extracts were administered by intratracheal aspiration at doubling doses (2.5-80 μg protein) 4X over a four-week period. Three days after the last exposure, serum and bronchoalveolar lavage fluid (BALF) were collected. The extracts' relative allergenicity was evaluated based on response robustness (lowest significant dose response compared to control (0 μg)). MACA induced a more robust serum total IgE response than HDM. However, in the antigen-specific IgE assay, a similar dose of both MACA and HDM was required to achieve the same response level. Our data suggest a threshold dose of MACA for allergy induction and that M. anisopliae may be similar to HDM in allergy induction potential.

A comparison of the allergic responses induced by Penicillium chrysogenum and house dust mite extracts in a mouse model

A report by the Institute of Medicine suggested that more research is needed to better understand mold effects on allergic disease, particularly asthma development. We compared the ability of the fungal Penicillium chrysogenum (PCE) and house dust mite (HDM) extracts to induce allergic responses in BALB/c mice. The extracts were administered by intratracheal aspiration (IA) at several doses (0, 2.5, 5, 10, 20, 40, and 80 μg) four times over a 4-week period. Three days after the last IA exposure, serum and bronchoalveolar lavage fluid (BALF) were collected. The relative allergenicity of the extracts was evaluated based on the lowest dose able to induce a significant response compared to control (0 μg) and the robustness of the response. PCE induced the most robust response at the lowest dose for most endpoints examined: BALF total, macrophage, neutrophil, and eosinophil cell counts, and antigen-specific IgE. Taken together, our data suggest that PCE may induce a more robust allergic and inflammatory response at lower doses than HDM.

PRACTICAL IMPLICATIONS

Our data suggest that Penicillium chrysogenum is a robust allergen and may be a more potent allergen source than house dust mite (HDM) in this mouse model. Two critical factors in the development of human allergic disease, exposure levels and sensitization thresholds, are unknown for most allergens including molds/fungi. Human exposure levels are not within the scope of this article. However, the data presented suggest a threshold dose for the induction of allergic responsiveness to P. chrysogenum. Additionally, P. chrysogenum as well as other molds may play an important role in asthma development in our society.

The relative allergenicity of Stachybotrys chartarum compared to house dust mite extracts in a mouse model

A report by the Institute of Medicine suggested that more research is needed to better understand mold effects on allergic disease, particularly asthma development. The authors compared the ability of the fungus Stachybotrys chartarum (SCE) and house dust mite (HDM) extracts to induce allergic responses in BALB/c mice. The extracts were administered by intratracheal aspiration (IA) at several doses (0, 2.5, 5, 10, 20, 40, and 80 microg) 4 times over a 4-week period. Three days after the last IA exposure, serum and bronchoalveolar lavage fluid (BALF) were collected. The relative allergenicity of the extracts was evaluated based on the lowest dose that induced a significant response compared to control (0 microg) and the linear regression slope analysis across the dose range. SCE induced a more robust response than HDM for BALF some inflammatory cells (macrophage and neutrophils), whereas HDM induced more robust BALF lymphocyte and eosinophil responses. Although SCE induced a more robust serum total immunoglobulin E (IgE) response than did HDM, the induction of a similar response in a functional, antigen-specific IgE assay required approximately twice as much SCE as HDM. Even though SCE demonstrates the ability to induce allergic responses in the mouse model, considering the importance and relevance of eosinophil, lymphocyte, and antigen-specific IgE in allergic airway disease, it is concluded that HDM is more potent than SCE in the induction of allergic responses. These data suggest a threshold dose for SCE allergy induction. Furthermore, in damp water-damaged environments, exposure to S. chartarum might easily exceed the sensitization threshold for a susceptible population.

Indoor environment in three North European cities in relationship to atopy and respiratory symptoms

BACKGROUND

In the European Community Respiratory Health Survey (ECRHS) I, the lowest prevalence of asthma and atopy was found in Reykjavík (Iceland) and Tartu (Estonia). The aim of this study was to compare home environments in Reykjavík and Tartu to a town with a higher prevalence of asthma and atopy (Uppsala, Sweden) in an attempt to identify factors in the indoor environment that could explain these differences.

METHOD

A random sample of 129 ECRHS II participants was included in this analysis at each of the three study centres. The subjects answered a questionnaire, blood was analysed for specific immunoglobulin E, a methacholine test was performed and home indoor measurements were taken.

RESULTS

The prevalence of atopy was 11.9% in Reykjavík, 35.5% in Uppsala and 28.2% in Tartu (P < 0.04). The level of indoor cat allergen was significantly lower in Reykjavík compared with Uppsala (P = 0.05). No mite allergens were identified in the 41 homes investigated in Reykjavík, while this was the case in 16% and 72% of the households in Uppsala and Tartu, respectively (P = 0.001). A positive association was found between asthma symptoms and cat allergen levels [odds ratio 1.53 (95% confidence interval 1.04-2.24)], while the levels of viable moulds were significantly associated with increased bronchial responsiveness.

CONCLUSIONS

Indoor exposure to allergens, moulds and bacteria was lower in Reykjavík than in the Swedish and Estonian centres. This finding indicates that the lower prevalence of allergic sensitization in Reykjavík may partly be related to lower indoor allergen exposure.

Primary prevention of allergy: avoiding risk or providing protection?

Primary prevention strategies of allergy so far have been aimed to fight allergy causes, by avoiding risk factors and inhibiting their mechanisms of action. The results of trials testing food or airborne allergen avoidance as a prevention strategy were, however, rather disappointing. A reverse approach for primary prevention of allergies aims to facilitate exposure to protecting factors which promote the induction of immunologic tolerance against innocuous antigens. These factors are associated with farming environment and a 'traditional lifestyle', but identification of these factors is quite difficult. Major candidates include food-borne microbes, helminths or their components, which are able to stimulate mucosal immunity, particularly in the gut. Similarly, new preventive and therapeutic strategies are being tested to induce specific food-allergen oral tolerance through the ingestion of progressively increasing doses of the offending food. This shifting of allergy prevention research from avoidance to tolerance induction will hopefully allow us to reverse the epidemic trend of allergy diseases.

Early-life allergen exposure and atopy, asthma, and wheeze up to 6 years of age

RATIONALE

Although it is widely assumed that the incidence of childhood respiratory allergies to common aeroallergens is directly related to allergen exposure in early life, few longitudinal studies have investigated this issue, and available data are scarce and mainly limited to high-risk groups.

OBJECTIVES

To assess, in a prospective manner and in a general population, the role of early life exposures to Der p1 and Fel d1 on the inception of sensitization and asthma.

METHODS

Pregnant women and their children were recruited for the Asthma Multicentre Infant Cohort Study. Overall, 1,611 newborns were initially enrolled in three cohorts in the United Kingdom and Spain. Der p1 and Fel d1 allergens were measured in household dust samples at 3 months of age for 1,474 (91.5%) participants, and skin prick tests were performed at 6 years of age on 1,182 (80.2%) participants. Wheeze and diagnosed asthma were reported in yearly questionnaires.

MEASUREMENTS AND MAIN RESULTS

Exposure to Der p1 early in life was not related to a positive specific prick test or to asthma or persistent wheeze at 6 years of age. Fel d1 showed an association with all these outcomes (third vs. first tertile; odds ratio, 4.43 for positive specific prick test and 2.6 for diagnosed asthma).

CONCLUSIONS

Dose-response relationships between allergen exposure and sensitization or asthma may be allergen specific and nonlinear; a minimum threshold level is needed to induce sensitization, but no dose-response relationship exists above this level. The effect of a particular allergen seems to be similar on atopy and asthma inception.

Bronchial responsiveness in atopic adults increases with exposure to cat allergen

RATIONALE

The association of asthma with sensitization and allergen exposure is known to be complex. There have been few studies of bronchial responsiveness in relation to both risk factors in adults.

OBJECTIVES

To determine the relation of bronchial responsiveness to allergen exposure and IgE sensitization in a community study taking into account the major determinants of bronchial responsiveness in adulthood.

METHODS

Cross-sectional data were drawn from 1,884 participants in 20 centers in the European Community Respiratory Health Survey follow-up, which included measurement of house dust mite and cat allergen in mattress dust samples, and IgE sensitization to four allergens. Bronchial responsiveness to methacholine was expressed as a continuous variable, and analyzed by multiple regression.

MEASUREMENTS AND MAIN RESULTS

The trend toward greater bronchial responsiveness with increasing exposure to cat allergen was greater in those sensitized to any of the four allergens than those not sensitized (p = 0.001); there was no significant interaction between cat sensitization and Fel d 1 exposure. No trend was found with house dust mite allergen exposure. The difference in bronchial responsiveness between those exposed to the highest levels compared with the lowest was approximately -2.02 doubling doses of PD20 (95% confidence interval, -3.06 to -0.97), and nearly as great in those exposed to more moderate levels.

CONCLUSIONS

Cat allergen exposure at moderate levels may be harmful to all atopic adults. The clinical implication is that it is insufficient to test patients with asthma for cat sensitization; all atopic individuals may benefit from reduced cat exposure.

House cleaning with chlorine bleach and the risks of allergic and respiratory diseases in children

Chlorine bleach or sodium hypochlorite can inactivate common indoor allergens. In this cross-sectional study we evaluated to what extent regular house cleaning with bleach can influence the risks of respiratory and allergic diseases in children. We studied a group of 234 schoolchildren aged 10-13 yr among whom 78 children were living in a house cleaned with bleach at least once per week. Children examination included a questionnaire, an exercise-induced bronchoconstriction test and the measurement of exhaled nitric oxide (NO) and of serum total and aeroallergen-specific immunoglobulin (Ig)E, Clara cell protein (CC16) and surfactant-associated protein D (SP-D). Children living in a house regularly cleaned with bleach were less likely to have asthma (OR, 0.10; CI, 0.02-0.51), eczema (OR, 0.22; CI, 0.06-0.79) and of being sensitized to indoor aeroallergens (OR, 0.53; CI, 0.27-1.02), especially house dust mite (OR, 0.43; CI, 0.19-0.99). These protective effects were independent of gender, ethnicity, previous respiratory infections, total serum IgE level and of family history of allergic diseases. They were however abolished by parental smoking, which also interacted with the use of bleach to increase the risk of recurrent bronchitis (OR, 2.03; CI, 1.12-3.66). House cleaning with bleach had effect neither on the sensitization to pollen allergens, nor on the levels of exhaled NO and of serum CC16 and SP-D. House cleaning with chlorine bleach appears to protect children from the risks of asthma and of sensitization to indoor allergens while increasing the risk of recurrent bronchitis through apparently an interaction with parental smoking. As chlorine bleach is one of the most effective cleaning agent to be found, these observations argue against the idea conveyed by the hygiene hypothesis that cleanliness per se increases the risk of asthma and allergy.

Acaricidal activities of some essential oils and their monoterpenoidal constituents against house dust mite, Dermatophagoides pteronyssinus (Acari: Pyroglyphidae)

The acaricidal activities of fourteen essential oils and fourteen of their major monoterpenoids were tested against house dust mites Dermatophagoides pteronyssinus. Five concentrations were used over two different time intervals 24 and 48 h under laboratory conditions. In general, it was noticed that the acaricidal effect based on LC(50) of either essential oils or monoterpenoids against the mite was time dependant. The LC(50) values were decreased by increasing of exposure time. Clove, matrecary, chenopodium, rosemary, eucalyptus and caraway oils were shown to have high activity. As for the monoterpenoids, cinnamaldehyde and chlorothymol were found to be the most effective followed by citronellol. This study suggests the use of the essential oils and their major constituents as ecofriendly biodegradable agents for the control of house dust mite, D. pteronyssinus.

Exposure to microbial components and allergens in population studies: a comparison of two house dust collection methods applied by participants and fieldworkers

Dust collection by study participants instead of fieldworkers would be a practical and cost-effective alternative in large-scale population studies estimating exposure to indoor allergens and microbial agents. We aimed to compare dust weights and biological agent levels in house dust samples taken by study participants with nylon socks, with those in samples taken by fieldworkers using the sampling nozzle of the Allergology Laboratory Copenhagen (ALK). In homes of 216 children, parents and fieldworkers collected house dust within the same year. Dust samples were analyzed for levels of allergens, endotoxin, (1-->3)-beta-D-glucans and fungal extracellular polysaccharides (EPS). Socks appeared to yield less dust from mattresses at relatively low dust amounts and more dust at high dust amounts than ALK samples. Correlations between the methods ranged from 0.47-0.64 for microbial agents and 0.64-0.87 for mite and pet allergens. Cat allergen levels were two-fold lower and endotoxin levels three-fold higher in socks than in ALK samples. Levels of allergens and microbial agents in sock samples taken by study participants are moderately to highly correlated to levels in ALK samples taken by fieldworkers. Absolute levels may differ, probably because of differences in the method rather than in the person who performed the sampling. Practical Implications Dust collection by participants is a reliable and practical option for allergen and microbial agent exposure assessment. Absolute levels of biological agents are not (always) comparable between studies using different dust collection methods, even when expressed per gram dust, because of potential differences in particle-size constitution of the collected dust.

Mold damage in homes and wheezing in infants

BACKGROUND

In most studies that investigate the association of mold or water damage and respiratory disorders in infants, the analysis is not adjusted for exposure to house dust mite (HDM), which is also a known cause of respiratory illnesses.

OBJECTIVE

To investigate the relationship between visually observable mold or water damage and HDM (Der f 1) levels and the prevalence of lower respiratory tract symptoms and allergen sensitization in infants of atopic parents as part of a prospective birth cohort study.

METHODS

On-site home visits (at the infants' age of 8 months) were performed to evaluate observable mold or water damage and HDM exposure. At a clinic visit near the infant's first birthday, medical histories, including parent-reported wheezing episodes, and a skin prick test to food and 15 common aeroallergens were conducted in 640 infants.

RESULTS

More than half of the homes were found to have mold or water damage, and 5% had major mold or water damage with visible mold at 0.2 m2 or more. Only 16% of homes had a HDM allergen (Der f 1) concentration of more than 2 microg/g. Major mold or water damage increased the risk of recurrent wheezing nearly 2 times in infants, 5 times in food or aeroallergen-sensitized infants, and 6 times in aeroallergen-sensitized infants. Neither visible mold or water damage nor HDM exposure was associated with sensitization to either mold or aeroallergens.

CONCLUSIONS

Visible mold was shown to be a significant risk factor for recurrent wheezing in infants at high risk of developing atopic disorders, whereas HDM exposure did not significantly increase the risk.

Association between nonspecific airway hyperresponsiveness and Arg16Gly beta2-adrenergic receptor gene polymorphism in asymptomatic healthy Japanese subjects

BACKGROUND

Nonspecific airway hyperresponsiveness (AHR), a cardinal feature of asthma, is thought to result from several genetic and environmental factors. Asymptomatic AHR in nonasthmatic healthy subjects might be a risk factor for the development of asthma. Genetic variations in codons 16 and 27 of the human beta(2)-adrenergic receptor (beta(2)-AR) alter receptor function in vitro and are associated with various asthma-related phenotypes, including asthma severity and AHR. To date, however, few reports have examined the impact of beta(2)-AR gene polymorphism on AHR in asymptomatic healthy subjects.

OBJECTIVE

To determine whether polymorphism of the beta(2)-AR gene (Arg16Gly and Gln27Glu) might influence nonspecific AHR in asymptomatic healthy Japanese subjects.

DESIGN AND PARTICIPANTS

A cohort of 120 asymptomatic healthy subjects was analyzed using a stepwise linear regression model. Nonspecific airway responsiveness was measured using a continuous methacholine inhalation method (Astograph; Chest; Tokyo, Japan). We used values of the cumulative dose of inhaled methacholine measured at the inflection point at which respiratory conductance starts to decrease (Dmin) as an index of AHR. Genotyping to identify polymorphisms at codons 16 and 27 was conducted using an assay combining kinetic real-time quantitative polymerase chain reaction with allele-specific amplification.

RESULTS

The Gly16Gly genotype was associated with lower Dmin values. The log Dmin value of asymptomatic healthy subjects carrying the Arg16 allele (Arg16/Arg or Arg16/Gly, n = 90) was 1.09 +/- 0.56 (mean +/- SD), while those homozygous for the Gly16 allele (n = 30) yielded a log Dmin value of 0.85 +/- 0.56 (p < 0.05).

CONCLUSION

This study indicates that a specific beta(2)-AR polymorphism at codon 16 might be a genetic determinant of AHR, as judged by methacholine-induced bronchoconstriction in asymptomatic healthy subjects.

Dust mite species and allergen concentrations in beds of individuals belonging to different urban socioeconomic groups in Brazil

BACKGROUND

Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis dust mites are among the most important agents of hypersensitivity reactions in human beings. However, a role of other mites in the etiology of these reactions has not yet been excluded.

OBJECTIVES

To investigate the nature of the dust mite fauna and the presence of Der p 1 (allergen 1 of Dermatophagoides pteronyssinus) and Blo t 5 (allergen 5 of Blomia tropicalis) on beds used by individuals with different socioeconomic backgrounds in Salvador, a major Brazilian city and to investigate possible associations of mite frequencies and allergen levels with (a) season of the year, (b) housing characteristics, (c) bed cleaning behaviors that could affect mite densities, and (d) allergy history.

METHODS

Dust samples were collected from 459 beds of 101 residences from two groups with different socioeconomic levels (hereafter called wealthy and poor groups) in the city of Salvador, Brazil, for the identification of mite species and determination of Der p 1 and Blo t 5 levels. History of allergy was collected using the ISAAC phase I questionnaire.

RESULTS

Eighty nine percent of the beds analyzed harbored at least one mite species. B. tropicalis was found in 71.8%, D. pteronyssinus in 39.9%, Cheyletus sp. in 33.9%, and Gohieria fusca in 21.1% of the beds. B. tropicalis was found with a similar frequency in beds of the two socioeconomic groups; D. pteronyssinus was found more frequently in the beds of the wealthy than of the poor group, whereas the reverse was observed with G. fusca. The concentrations of Der p 1 and Blo t 5 allergens exceeded the cut-off for sensitization of 2 microg/g of dust in 94.0% and 69.3% of the wealthy and poor group beds, respectively. No associations were found between history of allergy and mite species or between history of allergy and the concentrations of mite allergens.

CONCLUSIONS

The observation of B. tropicalis and D. pteronyssinus as the most frequently found mites is consistent with previous reports from tropical regions. The higher frequency of G. fusca in beds of individuals from the poor group than those from the wealthy group could be a consequence of different bed cleaning behaviors between the two groups.

Current eczema in children is related to Der f 1 exposure but not to Der p 1 exposure

BACKGROUND

Mite allergen exposure is an important risk factor for specific IgE production and is associated with asthma, hay fever and eczema. Whether these associations are independent of mite species has not been investigated so far.

OBJECTIVES

To investigate the influence of exposure to the major house dust mite (HDM) allergens Der p 1 and Der f 1 on sensitization, respiratory symptoms, and especially on eczema and related skin symptoms in 6-7-year-old children.

METHODS

In a cross-sectional study in Augsburg (Bavaria, Germany) 1669 school beginners (mean age 6.5 years) were investigated in 1996. The concentrations of Der p 1 and Der f 1 were measured in dust samples from mattresses of 1081 children by enzyme-linked immunosorbent assay. The prevalence of atopy-related health outcomes was assessed by questionnaire, dermatological examination, skin prick testing and determination of specific serum IgE concentrations by radioallergosorbent test. Information about covariates was taken from questionnaires and interview data. Logistic regression was used to adjust for confounding.

RESULTS

The mean concentrations of Der p 1 and Der f 1 were 0.68 and 0.79 microg g(-1) dust, respectively. The relationship between the two species-specific allergens in individual homes was poor (Pearson correlation 0.2). Influencing variables were bedroom-sharing (Der p 1) and social status of the parents (Der f 1). Respiratory diseases were positively associated with both allergen concentrations [odds ratio (OR) between 1.1 and 2.6]. These associations were significant for sneezing attacks (Der p 1 and Der f 1). Reported prevalence of current (in the last 12 months) itchy skin rash was significantly associated with exposure to Der f 1 only (OR 2.4, P < 0.003); also a diagnosis of atopic eczema on the day of investigation was positively associated with Der f 1 only (OR 1.8, P = 0.14).

CONCLUSIONS

Studies on the effects of HDM exposure on eczema and allergies should consider specific effects of different mite species. This might have implications on assessment of allergen exposure and consecutive prevention or therapeutic measures.

Nonlinear relations between house dust mite allergen levels and mite sensitization in farm and nonfarm children

BACKGROUND

Low sensitization rates to common allergens have been observed in farm children, which might be due to high exposure to microbial agents. It is not known how microbial agents modify the association between specific allergen exposure and sensitization.

OBJECTIVE

To examine the relations between house dust mite allergen exposure and mite sensitization in farm and nonfarm children and to assess the effects of microbial agents levels on this association.

METHODS

Major mite allergens of Dermatophagoides pteronyssinus (Der p 1) and Dermatophagoides farinae (Der f 1), endotoxin, beta(1,3)-glucans and fungal extracellular polysaccharides were measured in mattress dust of 402 children participating in a cross-sectional study in five European countries. Mite allergen (Der p 1 + Der f 1) levels were divided into tertiles with cut-offs 1.4 and 10.4 microg/g. Sensitization was assessed by measurement of allergen-specific immunoglobulin E against house dust mite.

RESULTS

Prevalence ratios of mite sensitization for medium and high when compared with low mite allergen levels were 3.1 [1.7-5.7] and 1.4 [0.7-2.8] respectively. Highest mite sensitization rates at intermediate exposure levels were consistently observed across country (except for Sweden) and in both farm and nonfarm children. The shape of the dose-response curve was similar for above and below median mattress microbial agent levels, but the 'sensitization peak' appeared to be lower for above median levels.

CONCLUSIONS

Our data suggest a bell-shaped dose-response relationship between mite allergen exposure and sensitization to mite allergens. In populations with high microbial agent levels and low sensitization rates, the curve is shifted down.

A multihazard, multistrategy approach to home remediation: results of a pilot study

Many residential hazards are disproportionately concentrated in older, urban dwellings and share common underlying causes, such as uncorrected moisture problems and inadequate maintenance and cleaning. Comprehensive and affordable approaches to remediation are needed, but the feasibility and efficacy of such approaches has not been well documented. To address this gap, a multihazard, multimethod intervention, addressing deteriorated lead-based paint and lead dust, vermin, mold, and safety hazards was pilot-tested in a sample of 70 pre-1940 dwellings. Dwellings received paint stabilization, dust lead cleaning, integrated pest management (IPM), mold cleaning, and safety devices, as needed. The median remediation cost for labor and materials was 864.66 dollars (range: 120.00-5235.33 dollars) per dwelling. Environmental conditions were evaluated prior to, immediately following, and an average of 5 months after remediation. Between the baseline and 5-month follow-up periods, significant reductions were achieved in the number of dwellings with multiple (i.e., three or four) problems (75% vs. 23%, P<0.0001); high levels of dust lead on floors and window sills (67% and 46% declines, P<0.01); evidence of cockroaches or rodents (43% and 36% declines, P<0.01); and fire, electrical and/or fall hazards (between 67% and 88% declines, P<0.01). Significant reductions were also observed in the geometric mean (GM) dust lead levels on floors and window sills (13.3 vs. 5.0 microg/ft2 and 210.6 vs. 81.0 microg/ft2, respectively, P<0.0001) and Blatella germanica (Blag1) levels among dwellings with elevated baseline levels (7.7 vs. 0.09 U/g, P<0.0001). Reductions in mold dust levels were of borderline statistical significance (50% decline, P=0.07). The greatest declines in dust lead and Blag1 levels occurred in dwellings having the highest baseline levels and, for Blag1, in dwellings in which occupants attended training sessions. These results indicate that a comprehensive approach to hazard remediation can be highly effective and cost efficient and that overall improvements can be maintained. Further research is needed to clarify the most effective sampling strategies, educational and behavioral interventions, and optimal intervention frequency.

Allergens in the pathogenesis of asthma: potential role of anti-immunoglobulin E therapy

Evidence suggests that allergy is a significant triggering factor in asthma in children and adults alike. In immunoglobulin (Ig) E-mediated allergic reactions, sensitization occurs when allergen-specific B cells are stimulated and switched to IgE antibody production by interleukin (IL)-4 and IL-13 provided by helper T cells type 2 (Th2). The IgE antibodies act by arming cells bearing either the high-affinity (FcepsilonRI) or low-affinity (FcepsilonRII or CD23) receptor. The subsequent interaction of allergen with IgE-FcepsilonRI complexes on mast cells and basophils causes cross-linking of receptors that triggers the release of a variety of inflammatory mediators, cytokines and chemokines. Therefore, the ability to lower circulating free IgE levels is desirable because most individuals are exposed to multiple allergens to which they are sensitive at any given time. Omalizumab (formerly known as rhuMAb-E25) is a recently developed humanized monoclonal anti-IgE antibody directed at the FcepsilonRI binding domain of human IgE. It inhibits binding of IgE to mast cells without provoking mast cell activation. Preliminary clinical data from randomized controlled trials have shown that the addition of omalizumab to standard asthma therapy reduces asthma exacerbations and decreases inhaled corticosteroid and rescue medication use. The compound is also well tolerated. Omalizumab represents a novel therapeutic approach in the management of asthma.

Feasibility of using subject-collected dust samples in epidemiologic and clinical studies of indoor allergens

Studies of indoor allergen exposures are often limited by the cost and logistics of sending technicians to homes to collect dust. In this study we evaluated the feasibility of having subjects collect their own dust samples. The objectives were to compare allergen concentrations between subject- and technician-collected samples and to examine the sample return rate. Using a dust collection device and written instructions provided to them by mail, 102 subjects collected a combined dust sample from a bed and bedroom floor. Later the same day, a technician collected a side-by-side sample. Dust samples were weighed and analyzed for the cat allergen Fel d 1 and the dust mite allergen Der p 1. Fifty additional subjects who were enrolled by telephone were mailed dust collection packages and asked to return a dust sample and questionnaire by mail. A technician did not visit their homes. Correlations between subject- and technician-collected samples were strong for concentrations of Fel d 1 (r = 0.88) and Der p 1 (r = 0.87). With allergen concentrations dichotomized at lower limits of detection and clinically relevant thresholds, agreements between methodologies ranged from 91 to 98%. Although dust weights were correlated (r = 0.48, p < 0.001), subjects collected lighter samples. Among the group of 50 subjects, 46 returned a dust sample and completed questionnaire. The median number of days to receive a sample was 15. With some limitations, subject-collected dust sampling appears to be a valid and practical option for epidemiologic and clinical studies that report allergen concentration as a measure of exposure.

Lack of de novo sensitization to tropomyosin in a group of mite-allergic patients treated by house dust mite-specific immunotherapy

BACKGROUND

There is some evidence that specific immunotherapy may induce de novo sensitization to proteins contained in the allergen extract. This raises the possibility that the novel sensitization to cross-reacting allergens may cause food allergies.

OBJECTIVE

The aim of this study was to assess whether injection of mite-specific immunotherapy (SIT) may induce sensitization to shrimp tropomyosin.

METHODS

Seventy mite-allergic subjects who did not show any shrimp sensitization at baseline were followed up for at least 3 years. Thirty-one of them underwent a 3-year SIT course, 39 served as controls. At the follow-up visit, SPTs with both fresh shrimp and commercial extract were performed, and patients underwent an open oral challenge with shrimp.

RESULTS

Neither patient nor control had become sensitized to shrimp allergens at the end of the study period. Both patients and controls reported the regular intake of crustaceans and/or molluscs.

CONCLUSION

Injection SIT with house dust mite extracts does not seem to induce de novo tropomyosin sensitization in mite-allergic patients.

Quantitation of house dust mite allergens (Der f 1 and group 2) on the skin and hair of dogs

OBJECTIVE

To determine the concentration of house dust mite (HDM) allergens, Der f 1 and group 2, on the skin and hair of dogs and whether associations exist between the presence of Der f 1 and group 2 allergens on the skin and hair of dogs and household and dog characteristics.

ANIMALS

63 pet dogs from 50 homes.

PROCEDURE

Dogs were weighed and body surface area in square meters was determined. Skin and hair samples were obtained by vacuuming dogs. Collected dust was analyzed by use of standard ELISA techniques.

RESULTS

HDM allergen was detected in 21 of 59 skin and hair samples. Presence of group 2 allergen on skin and hair of dogs was significantly associated with long hair, compared with short or medium length hair. Median house dust sample concentrations of Der f 1 and group 2 allergens were high in homes with dogs that had skin and hair samples that were positive for Der f 1 and group 2 allergens. Dogs with skin and hair samples that were positive for Der f 1 and group 2 allergens resided in homes with a high number of house dust samples that were positive for Der f 1, group 2, or both allergens and in homes with a mean house dust sample allergen concentration of > or =2 microg/g of dust.

CONCLUSIONS AND CLINICAL RELEVANCE

Associations exist between environmental HDM allergen concentrations and HDM allergens on the skin and hair samples of dogs. Environmental allergen load is a major factor in accumulation of allergens on the skin and hair of dogs.

[Childhood allergies in Reunion Island: is there any difference with metropolitan France?]

BACKGROUND

The present study had three aims: to estimate for the first time with standardized methodology allowing international comparisons the prevalence and the severity of childhood allergies in Reunion Island, to determine their risk factors and to make a comparison with metropolitan France.

METHODS

The same standardized protocol (ISAAC) was used in population-based samples of adolescents recruited in metropolitan France between 1993 and 1994 (n=18555) and in Reunion Island in 2000 (n=2 362).

RESULTS

Compared to metropolitans, the adolescents living in Reunion Island suffered significantly more from asthma in the past Year and in life (22 vs 13% and 19 vs 13% respectively). The trend was less clear for allergic rhinitis and eczema since in the case of these manifestations the adolescents reported more symptoms (27 vs 16% et 14 vs 10%, respectively) whereas the metropolitans reported more lifetime diagnostic labels (14 vs 17% et 18 vs 23%, respectively). In Reunion Island, allergies were slightly more severe (1.1 vs 0.8% for severe asthma and 15 vs 2% for eczema). Furthermore, 68% of asthmatics who had severe asthma attacks in the past Year and more than a third of adolescents with severe asthma did not take any asthma medication, which is different from the metropolitan situation. Risk factors for allergies were the same in Reunion Island and in metropolitan France, except the ownership of a pet in the first Year of life, which was not protective against the development of allergies as recently shown in some western countries but was a risk factor.

CONCLUSIONS

Asthma and allied diseases are less frequent in metropolitan France than in Reunion Island where management appears to be insufficient. Improvement in prevention and management plans are required in Reunion Island.