Patterns of IgE sensitization in house dust mite-allergic patients: implications for allergen immunotherapy.

BACKGROUND: Understanding patterns of IgE sensitization in Dermatophagoides-allergic patients living in various geographical areas is necessary to design a product suitable for worldwide allergen immunotherapy (AIT). METHODS: Using a HIFI Allergy customized microarray assay, IgEs specific for 12 purified allergens from Dermatophagoides pteronyssinus or D. farinae were assessed in sera from 1302 house dust mite (HDM)-allergic patients living in various areas. Comprehensive mass spectrometric (MS) analyses were conducted to characterize HDM extracts, as well as purified bodies and feces. RESULTS: Patterns of IgE reactivity to HDM allergens are comparable in all cohorts of patients analyzed, encompassing adults and 5- to 17-year-old children, as well as American, Canadian, European, and Japanese patients. Overall, >70% and >80% of HDM-allergic patients are sensitized to group 1 and group 2 allergens, respectively, from D. pteronyssinus and/or D. farinae species. Furthermore, 20-47% of patients also have IgEs to allergens from groups 4, 5, 7, 13, 15, 21, and 23. All patients have IgEs to allergens present in mite bodies and feces. MS-based analyses confirmed the presence of mite allergens recorded by IUIS in D. pteronyssinus and D. farinae extracts, with groups 2, 8, 10, 11, 14, and 20 prominent in bodies and groups 1, 6, 18, and 23 well represented in feces. CONCLUSIONS: Mite-specific AIT should rely upon a mixture of D. pteronyssinus and D. farinae extracts, manufactured from both feces and bodies. Such a combination is appropriate to treat children and adult Dermatophagoides-allergic patients from Asia, Europe, and North America.

Allergic airway diseases in a tropical urban environment are driven by dominant mono-specific sensitization against house dust mites.

BACKGROUND: Southeast Asian populations are increasingly affected by allergic airway diseases. Etiology and specific causes, however, are still unknown. The aim of this study is therefore to identify allergens and risk factors for the high prevalence of allergic airway disease in the tropical urban environment. METHODS: Symptoms of allergic rhinitis (AR), asthma, and allergic dermatitis were recorded in two independent cohorts of 576 and 7373 ethnic Chinese individuals living in Singapore. Reactivity against common allergens was determined by skin prick tests (SPT); specific immunoglobulin E (sIgE) titers against 12 common allergens, as well as total serum IgE (tIgE), were measured in the smaller cohort. RESULTS: Immunoglobulin E sensitization was almost exclusively directed against house dust mite (HDM) allergens. More than 80% of individuals were HDM-sIgE positive. Of these, less than 30% also had sIgE for other allergens, and similarly, few of the HDM-sIgE-negative individuals reacted to other allergens. Titers for HDM-sIgE were 8-30 times higher than other non-HDM allergen titers and correlated directly with total serum tIgE levels. Migrants from nontropical countries typically arrived with low or undetectable HDM-sIgE but developed substantial titers in a time-dependent fashion. Importantly, prolonged stay in Singapore also resulted in the manifestation of AR and asthma symptoms, contributing to some of the highest national prevalence rates worldwide. CONCLUSION: In a tropical urban environment, the allergic response is dominated by a single allergen class. The mono-specific IgE sensitization against HDM translates into increased prevalence of allergic airway diseases, which now impact a large proportion of the population in Singapore.

Multiple wheat flour allergens and cross-reactive carbohydrate determinants bind IgE in baker's asthma.

BACKGROUND: Several wheat flour allergens relevant to baker's asthma have been identified in the last 25 years. The aim of this study was to determine the frequency of sensitization to these allergens in German bakers. METHODS: Using recombinant DNA technology, the following wheat flour allergens were cloned, expressed in Escherichia coli and purified: five subunits of the wheat α-amylase inhibitors (WTAI-CM1, WTAI-CM2, WTAI-CM3, WDAI-0.19 and WMAI-0.28), thioredoxin, thiol reductase or 1-cys-peroxiredoxin homologues, triosephosphate-isomerase, αß-gliadin, serpin, glyceraldehyde-3-phosphate-dehydrogenase, a nonspecific lipid transfer protein (nsLTP), dehydrin, profilin and peroxidase. In addition, ImmunoCAPs with the recombinant allergen ω-5-gliadin and two cross-reactive carbohydrate determinants (CCDs), horse radish peroxidase (HRP) and the N-glycan of bromelain (MUXF), were used. Specific IgE was measured in wheat flour-positive sera from 40 German bakers with work-related asthma/rhinitis and 10 controls with pollinosis. RESULTS: Thirty bakers (75%) had IgE to at least one of the 19 single allergens. Most frequent was IgE to WDAI-0.19, HRP and MUXF (25% each), followed by WTAI-CM1 (20%), thiol reductase (16%), WTAI-CM3 (15%), WTAI-CM2 and thioredoxin (12.5%), WMAI-28, triosephosphate-isomerase, αß-gliadin (10%), 1-cys-peroxiredoxin (7.5%), dehydrin, serpin, glyceraldehyde-3-phosphate-dehydrogenase (5%), ω-5-gliadin, nsLTP and profilin (2.5%). Fifteen bakers (38%) had IgE to any α-amylase inhibitor and 12 (30%) to at least one CCD. The controls reacted exclusively to CCDs (80%), profilin (60%), thioredoxin (30%), triosephosphate isomerase and nsLTP (10%). CONCLUSIONS: The single allergen sensitization profiles obtained with 17 recombinant wheat flour allergens and two CCDs revealed no major allergen for German bakers. The highest frequencies were found for α-amylase inhibitors and CCDs.

Mite sensitization among Latina women in New York, where dust-mite allergen levels are typically low.

UNLABELLED: In New York (NY), Latinos often have greater asthma morbidity than other ethnicities, and dust-mite sensitization is common despite low allergen levels. We investigated mite allergen exposure and sensitization in atopic and/or asthmatic women, the majority being Puerto Rican. Women (n = 274) recruited for a birth cohort study were visited postnatally. Dust from their homes was analyzed for mite allergens (Der f 1, Der p 1, and Blo t 5). Serum was analyzed for total and allergen-specific IgE. Thirty-seven percent were sensitized to Dermatophagoides pteronyssinus, 34% to Dermatophagoides farinae, and 21% to Blomia tropicalis. Only 5% of NY homes had levels of Der f 1 >2 microg/g; none had Blo t 5 or Der p 1 above this level. Caribbean or Latin American birthplace (a proxy for childhood exposure) was not associated with mite sensitization. Sensitization to D. pteronyssinus and D. farinae was associated with a report of doctor-diagnosed asthma [Odds ratio (OR) = 3.27, P = 0.003; OR = 2.81, P = 0.010, respectively]; sensitization to any mite was associated with asthma medication use in the past 12 months (OR = 3.12, P = 0.004). These associations held even after adjustment for cockroach, mouse, and cat sensitization. PRACTICAL IMPLICATIONS: Despite the low concentrations of mite allergen in our community, many of the women in the atopically enriched cohort were sensitized to mites, even Blomia tropicalis which is typically found only in tropical environments.

Collembola are unlikely to cause human dermatitis.

Abstract There have been several unconfirmed case reports of dermatitis caused by Collembola (springtails). We recently investigated two nurses with dermatitis suspected to be caused by Drepanura Schött (Collembola: Entomobryidae). IgE antibodies to Collembola proteins were not detected in sera from the nurses and skin tests with the Collembola extract and crushed whole Collembola were negative in both the nurses and volunteers. This study suggests that the springtail Drepanura may not cause human dermatitis and that other organisms and organic matter that are also found in the moist environment inhabited by Collembola might instead be responsible.

Home exposures to environmental tobacco smoke and allergic symptoms among young children in Singapore.

BACKGROUND: Research relating environmental tobacco smoke (ETS) exposures have focused on childhood asthma. There have been fewer studies with conflicting results performed on associations of ETS exposures with allergic symptoms. We are interested to see if ETS exposures in the homes are associated with allergic symptoms among preschool children in Singapore where public smoking is banned. METHODS: A cross-sectional study adopting an expanded and modified ISAAC (International Study on Asthma and Allergies in Childhood) questionnaire for the evaluation of asthma and allergies was conducted on 6,794 children attending 120 randomly selected child care centers. Specific information on demographics and ETS exposures was obtained. Adjusted prevalence ratios (PRs) and 95% confidence intervals (CIs) were determined using Poisson multivariate regression with a log-link function and robust variance estimates as recommended for cross-sectional studies. RESULTS: The response proportion was 70.0%, and 4,759 children from 97 centers participated. After adjusting for covariates, it was found that home ETS exposure was associated with increased risks of current symptoms of rhinitis (PR 1.23; 95% CI 1.01-1.50) and rhinoconjunctivitis (PR 1.79; 95% CI 1.26-2.54). These associations followed dose-response trends with respect to number of cigarettes smoked or smokers in the homes. Home ETS exposures were also associated with higher PRs of wheeze, nocturnal cough and doctor-diagnosed asthma. Compared with paternal smoking, higher risks of the above outcomes were found for maternal smoking. CONCLUSION: Home ETS exposure is a risk factor associated with rhinitis and asthma among preschool children.

Viability and adipogenic potential of human adipose tissue processed cell population obtained from pump-assisted and syringe-assisted liposuction.

BACKGROUND: Correcting soft tissue defects by autologous fat grafting has been a routine procedure in plastic surgery. Liposuction material for autologous fat grafting is normally obtained using a hand-held syringe. The pump-assisted liposuction technique is not used because of the belief that cells in the harvested fat tissue are necrotic from the physical forces created by the vacuum pump liposuction machine. OBJECTIVE: The metabolism and adipogenic potential of cultured mesenchymal precursor cells processed from pump and syringe lipoaspirates were studied. METHODS: Metabolic estimates were determined with alamarBlue assay. These cells were also induced along the adipogenic lineage with adipogenic induction factors. The extent of adipogenic differentiation was measured using a digital photo counting software. RESULTS: The cells obtained by pump-assisted liposuction are viable, have comparable metabolic activity and adipogenic potential which are comparable to cells using the syringe for aspiration. CONCLUSION: The implications of this study are that pump-assisted liposuction might be a possible alternative to aspirating adipose tissue for reimplantation during reconstruction procedures.

Piezoelectric quartz crystal based label-free analysis for allergy disease.

This work presents a piezoelectric (Pz) quartz crystal based label-free quantification of total IgE and allergen-specific IgE in human sera for allergy testing. An evaluation of the different brands of crystals was first initiated with respect to variability in mass sensitivity, frequency measurement reliability and stability, and surface roughness. Thereafter, for total IgE quantification. a direct assay format was adopted. By means of thioctic acid (TA) and coupling reagents, anti-human IgE antibodies were immobilized on AT-cut Pz crystals (10 MHz). The modified crystals could detect serum IgE directly corresponding to a downward frequency shift. The results showed that silver-coated crystals as compared with their gold-coated counterparts provided approximately 1.5 times higher mass detection sensitivity for total IgE in the range of 5-300 IU/ml with a linear regression line, y = 1.8957 x + 1.5603, R2 = 0.995. For the detection of allergen-specific IgE, a sandwiched assay format was used. As the allergen-modified sensor surface captured various classes of associated antibodies (IgE, IgG, etc) and interfering serum proteins as well, the initial frequency shift downwards caused by sera sample incubation would not be proportional to specific IgE levels. Thus, following sample incubation, a second incubation step with secondary anti-human IgE was added to recognize IgE from other bound substances. The frequency shift after secondary antibody binding reflected the amount of allergen-specific IgE proportionally. Compared with 10 MHz crystals, the 20 MHz counterparts provided approximately four times higher mass detection sensitivity for allergen specific IgE in the range of 0.15-17.5 IU/ml with a linear regression line, y = 50.525 x + 107.777, R2 = 0.954. Total IgE and allergen specific IgE assay results of real patients' sera using the Pz sensors agreed well with those obtained by commercially available test kits with correlation coefficient 0.96-0.98. The possibility of regenerating the quartz crystals for further re-use was also dealt with.

Seasonal variation in respiratory syncytial virus chest infection in the tropics.

Respiratory syncytial virus (RSV) is the most important cause of lower respiratory tract infection (LRTI) in young children. We determined if there was a seasonal variation in Malaysia in the incidence of RSV infection in young children admitted with LRTI, and possible associations of RSV infection with local meteorological parameters. A total of 5,691 children, aged less than 24 months and hospitalized with LRTI (i.e., bronchiolitis and pneumonia) between 1982-1997, were included in this study. Nasopharyngeal samples were collected and examined for RSV by immunofluorescence, viral culture, or both. Seasonal variations were determined by analyzing the monthly RSV-positive isolation rate via time series analysis. Possible correlations with local meteorological parameters were also evaluated.RSV was isolated in 1,047 (18.4%) children. Seasonal variations in RSV infection rate were evident and peaked during the months of November, December, and January (test statistics [T] = 53.7, P < 0.001). This seasonal variation was evident for both bronchiolitis and pneumonia categories (T = 42.8 and 56.9, respectively, P < 0.001). The rate of RSV infection appeared to correlate with the monthly number of rain days (r = 0.26, P < 0.01), and inversely with the monthly mean temperature (r = -0.38, P < 0.001). In the tropics, seasonal variations in the incidence of RSV infection are evident, with an annual peak in November, December, and January. This information provides a guide for healthcare provisions and implementation of RSV prevention.

Economic burden of varicella in Singapore--a cost benefit estimate of implementation of a routine varicella vaccination.

Varicella is a common childhood illness that can result in significant morbidity and mortality. As early as 1995, recommendations for routine varicella vaccination have been published, but have not been universally implemented, with cost of vaccination as a major reason. Though available from 1996, the vaccine has yet to be routinely implemented in Singapore. We set out to assess the economic burden of varicella and the cost-benefit of adding a varicella vaccine to the existing immunization schedule in Singapore. In this study, using data from 1994--1995 the direct cost estimates were based on all levels of medical care; inpatient care, emergency room visits, primary health care and medication. Indirect costs were estimated from the cost of time lost by patients and their families attending to medical needs, as well as loss of productivity due to absenteeism. The cost of a vaccination program targeted at 15-month old infants receiving concomitant measles-mumps-rubella immunization was also assessed. The cost-benefit ratio was then estimated. The total cost of varicella in Singapore was estimated to be US$11.8 million per annum. The loss of productivity accounted for a large proportion of the total cost as a lot of parents took leave when their children were ill. The estimates of total cost represent approximately US$188 per varicella case per year. In comparison, the cost of a vaccination program was found to be US$3.3 million per annum. The cost per case averted was US$104. From a societal point of view, for every dollar invested in a vaccination program, we would save about US$2 dollars.

Presence of domestic pets and respiratory symptoms in asthmatic children.

The allergens of domestic pets such as cats, dogs and birds, have been known to sensitive predisposed individuals. In Singapore, approximately 25% to 35% of our atopic populations are sensitised to cat, dog or bird feather allergens. It is not known, however, if the presence of such domestic pets would translate to higher rates of sensitisation, or more importantly, give rise to increased respiratory symptoms. This study evaluated the association between the presence of domestic pets at home and the prevalence of respiratory symptoms among asthmatic children in Singapore. The parents of 1517 doctor-diagnosed asthmatic children were interviewed using the American Thoracic Society-Division of Lung Diseases respiratory questionnaire. More than 20% were found to have domestic pets (cats, dogs or birds) at home. Of these, those with exposure to passive smoke in the home were excluded. A total of 188 current pet owners (cats, dogs and birds) were demographically-matched for sex, race and socio-economic status (type of housing) to those without pets, past or current. Compared to those without pets, asthmatic children with pets at home had a higher prevalence of coughing with cold [relative risk (RR) 1.30; 95% confidence interval (CI) 1.01 to 1.69]; wheezing with cold (RR 1.42; CI 1.07 to 1.90), wheezing with shortness of breath (RR 1.33; CI 1.00 to 1.82), exercise-induced wheezing (RR 1.68; CI 1.10 to 2.56); and increased phlegm production or congestion with cold (RR 1.38; CI 1.00 to 1.91). This study suggests that the presence of domestic pets increases the prevalence of respiratory symptoms in asthmatic children. Those with predisposition to these allergens should avoid having these pets in the home or take specific precautions in avoiding their allergens.

Utilization of healthcare resources for asthma in Singapore: demographic features and trends.

This study examined the healthcare utilization patterns for asthma in Singapore, a tropical island city-state, between 1986 and 1993. Asthma was ranked fifth among principal conditions with the highest number of discharges in Singapore (2.4 discharges per 1,000 population per annum). Among the 0-14 year-olds, asthma was ranked second, only after accidents and injuries, as the condition with the highest number of discharges (5.2 per 1,000). It was estimated that there were approximately 20,000 accident and emergency (A & E) room visits for asthma per annum (7.0 visits per 1,000 population per annum). There were, however, no significant changes in the number of hospitalized or emergency room cases for asthma over the period of analysis. In the primary healthcare setting, asthma ranked 6th among the leading conditions seen by the general practitioners and government polyclinics (15 visits per 100 population per annum). Among under 15 year olds, asthma (37 visits per 100 age-adjusted population per annum) ranked as the second leading condition behind upper respiratory tract infections. This study has shown that asthma causes a significant amount of morbidity in the Singapore community.

Factors associated with increased respiratory symptoms among asthmatic children in Singapore.

Asthma is a common cause of childhood morbidity. The objective of the present study was to evaluate the factors associated with increased asthma morbidity among asthmatic children in Singapore. A cohort of primary school children (n = 6,404, aged 6-13 years) were evaluated using the American Thoracic Society and the Division of Lung Diseases of the National Heart, Lung and Blood Institute, USA (ATS-DLD) respiratory questionnaire. A total of 2,222 of 6,404 children (34.8%) was found to have reported symptoms of wheezing. Of these, 899/2,222 (40.5%) reported symptoms of "increased asthma morbidity". This was associated with the younger age group, male sex and higher socio-economic status. In addition, concurrent or past allergies were strongly associated with increased asthma morbidity, while premature birth and a history of prior childhood respiratory illnesses and Infections were predictive of greater asthma morbidity. No association was found between increased morbidity and presence of domestic pets, parental smoking, childcare attendance, and the season of birth.

Culture of Blomia tropicalis and IgE immunoblot characterization of its allergenicity.

Blomia tropicalis is an important triggering factor for allergic diseases such as asthma, rhinitis and atopic dermatitis in tropical and subtropical regions, which climate favours the growth of this species. Our previous mite fauna study revealed that Blomia tropicalis is the most dominant species present in Singapore house dust The main objective of this study is to establish a mass culture of Blomia tropicalis for further characterization of the antigenic and molecular properties of this mite. Approximately one gram of mites could be obtained for every 300-gram of culture medium by culturing under natural condition with a mean annual temperature of 30 degrees C and a mean relative humidity of 80%, and harvested by modified Tullgren funnel. Allergen characterization by IgE immunoblot analysis with crude mite extracts showed some IgE reactivity differences between Blomia tropicalis mite extract from Singapore and Colombia. The possible reasons for these findings are the quality and source of the mite protein extracts used, or selective differences in the population under evaluation. Further, the atopic sera tested showed differences in the pattern and Intensity of IgE immunoblot reactivity to crude extracts of Blomia tropicalis and Dermatophagoides pteronyssinus, the other highly prevalent mite in Singapore. These data support the existence of species-specific allergens. In conclusion, we have been successful in setting up B. tropicalis mass cultures and have prepared extracts of high allergenicity.

House dust mite allergen levels in a Singapore hospital.

House dust mite allergens constitute one of the most important allergens in house dust. In this study, the levels of two common dust mite allergens, Der p I and Der f I, in a general hospital in Singapore were evaluated. Our results showed that these allergens were detected in 42/74 (or 57%) of the dust samples. Der p I was found to be the predominant allergen detected (p < 0.001). The allergen levels were, however, low with only 1/74 having a Der p I concentration above 2 micrograms g-1 dust. None of the samples had Der f I concentrations above this level. Of the various niches studied (mattresses, pillows, sofas, carpets, blinds and floors), the blinds and floors had the lowest concentration of allergen (p < 0.05). These low levels in the hospital compared to homes were attributed to the vigorous cleaning schedule in the hospital, the use of plastic to encased mattresses and pillows, vinyl covered sofas and vinyl lined floors. These practices may be adopted in the home as a means to reduce mite allergen exposure.

Allergens of Bipolaris species.

Skin prick tests done previously revealed a significantly higher percentage of sensitization to an extract of Bipolaris sp. among atopic individuals (34/147, 23.1%) compared to non-atopic individuals. Bipolaris-specific IgE levels were quantified in sera from a representative group of 38 individuals using the Fluorescence Allergosorbent Test (FAST). Result obtained by FAST were found to be comparable to the skin prick test results (r2 = 0.60, p < 0.001 for IgE levels vs wheal sizes; r2 = 0.44, p < 0.001 for IgE levels vs erythema sizes). Characterisation of the extract's allergenic component by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) showed 28 protein bands with molecular weights (MW) ranging from 11 kDa to above 100 kDa. Immunoblotting with sera of 10 Bipolaris-sensitive (skin prick test, 3 +) individuals showed that Bipolaris spore extract contained at least 4 IgE binding proteins (MW 11-13 kDa, 16-17 kDa, 20-22 kDa and 36 kDa). All 10 sera reacted to the protein at MW 20-22 kDa, 2 sera with MW 11-13 kDa, 3 sera with 16-17 kDa and 6 sera with 36 kDa. This study has thus demonstrated that spores of Bipolaris sp. contain allergenic components which may elicit IgE-mediated reactions.

Sensitization to Blomia tropicalis and dermatophagoides pteronyssinus-a comparative study between Singapore and Taiwan.

Blomia tropicalis (Bt) and Dermatophagoides pteronyssinus (Dp) are the predominant domestic mites species in Singapore and Taiwan. This study aims to characterize and compare the mite sensitization profiles in both countries. Skin prick tests were performed on 203 Singaporeans with Dp and Bt crude extracts. In vitro IgE and IgG4 reactivity to extracts and specific allergens (Der p 1, Der p 2 Der p 5 and Blo t 5) were determined by immunoassays. Approximately 91% of the tested Singaporeans were skin test positive for both Bt and Dp. Both populations share similar frequencies of in vitro IgE reactivity to all the allergens tested, but they differ in the pattern and magnitude of allergen sensitization. Although Der p 1, Der p 2 and Blo t5 are major sensitizing allergens in both countries, Blo t 5 is a more potent one in Singapore, probably reflecting the high level of exposure to Bt. The unique major Bt and Dp allergens should be included for precise diagnosis and effective immuno-therapeutic treatment of mite allergy in both countries.

Ethnic differences in genetic susceptibility to atopy and asthma.

The genetics of asthma and atopy is complex, but can be approached by studies of both candidate genes and mapping of susceptibility loci. Genetic factors conferring susceptibility to disease may vary among ethnic groups. We present our experience with some candidate gene studies for asthma and atopy and susceptibility locus mapping for linkage to chromosome 5q.