Use of a chimeric ELISA to investigate immunoglobulin E antibody responses to Der p 1 and Der p 2 in mite-allergic patients with asthma, wheezing and/or rhinitis

BACKGROUND: Sensitization to indoor allergens, particularly to dust mites, is a strong risk factor for asthma in children and adults. Assessment of sensitization is carried out using in vivo and in vitro tests to detect specific IgE antibodies. OBJECTIVE: To investigate IgE antibody responses to mites in patients with asthma, wheezing and/or rhinitis, using chimeric ELISA to measure specific IgE antibodies to mite allergens Der p 1 and Der p 2. METHODS: Specific IgE antibodies to Der p 1 and Der p 2 were quantified by chimeric ELISA, and compared with IgE to Dermatophagoides pteronyssinus (Dpt) measured using the CAP system (Pharmacia). A panel of sera from 212 patients with asthma, wheezing and/or rhinitis and 11 controls was analysed. RESULTS: There was a significant correlation between IgE to Dpt measured by CAP and IgE to Der p 1 (r = 0.81, P < 0.001), Der p 2 (r = 0.79, P < 0.001) and combined Der p 1 and Der p 2 (r = 0.86, P < 0.001). Seventy per cent of all patients had IgE to Dpt, and of those, 76.5% had IgE to Der p 1, 79.2% had IgE to Der p 2 and 83.1% had IgE to Der p 1 and Der p 2 combined. Considering the cut-off level of 2 IU/mL of IgE to either Der p 1 or Der p 2, the predictive value for a positive IgE to Dpt by CAP was greater than 95%. CONCLUSIONS: The chimeric ELISA allowed accurate quantification of IgE antibodies to Dpt allergens Der p 1 and Der p 2, and it could be useful for studying immune responses to mites in patients with asthma and/or rhinitis.     

Immunogenetics of atopic asthma: association of DRB1*1101 DQA1*0501 DQB1*0301 haplotype with Dermatophagoides spp.-sensitive asthma in a sample of the Venezuelan population

BACKGROUND: Genes linked to the major histocompatibility complex (MHC), have been implicated in atopic asthma. Asthma is highly prevalent in the Venezuelan population (estimated at 20%) and genetic markers are needed to identify populations at risk and plan intervention strategies. OBJECTIVE: To study the influence of the MHC class I and class II genes in the susceptibility to atopic asthma. METHODS: MHC-class I HLA-A, -C, -B and MHC-class II HLA-DR, -DQ, -DP gene haplotype frequencies were determined in 135 Venezuelan mestizos, 71 belong to 20 atopic asthmatic families and 64 unrelated controls. The index cases were 20 atopic asthmatics with positive skin-prick tests and specific serum immunoglobulin E (IgE) for Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f). To ascertain the genes associated with susceptibility to atopy and/or asthma, two control groups were studied, 41 non-atopic subjects with skin-prick negative test, and undetectable levels of specific IgE and 23 non-asthmatic atopic subjects with detectable specific IgE to Der p and Der f. A linkage analysis was performed in those families with two or more atopic siblings (with or without asthma). RESULTS: MHC-class I genes analysis showed that HLA-Cw7 was absent in the asthmatic patients studied, whereas the frequency of this allele was 14.3% in non-atopic controls (P = 0.0 17, PC = 0.19) and 20.8% in the atopic controls (P = 0.0066, PC = 0.07). MHC-class II gene analysis showed a significant increase of the HLA-DRB1*11 in the asthmatic patients compared with non-atopic controls (allele frequencies of 25.6 vs 4.4% P = 0.0017, PC = 0.02). There were no significant differences among asthmatic and atopic controls in the frequency of HLA-DRB1*11 (25.6 vs 17.4%). In contrast, the HLA-DRB1*1101+ haplotypes were significantly higher in asthmatics compared with atopic and non-atopic controls (19.6% vs 2.2% vs 2.3%, PC<0.05). The HLA-DRB1*1101, DQA1*0501, DQB1*0301 haplotype was found significantly increased in the patients vs non-atopic controls (15.4 vs 1.1%, PC< 0.01). The serum levels of specific IgE were detectable in both atopic asthmatics and atopic controls; however, it was higher in atopic asthmatics vs atopic controls Der p (median, 58.7 vs 2.7 kU/L, P<0.001) and Der f (median, 46.9 vs 2.7 kU/L, P<0.001). No linkage between MHC genes and mite-atopy could be documented on informative families with two or more atopic siblings. CONCLUSIONS: We have identified an association between the haplotype HLA-DRB1*1101, DQA1*0501, DQB1*0301 and atopic asthma that confers susceptibility to develop mite-sensitive asthma to atopics (relative risk, RR 8.2), and to non-atopic controls (RR = 15.8) that carry this haplotype. Conversely, the allele HLA-Cw7 was absent in the asthmatics studied and had higher frequencies in the atopic (RR = 0.05) and non-atopic (RR = 0.08) controls. Thus, it may have a protective role for developing atopic asthma in the population studied.     

IgE responses to Dermatophagoides pteronyssinus native major allergens Der p 1 and Der p 2 during long-term specific immunotherapy

We investigated by ELISA the IgE response to whole extract of the house-dust mite Dermatophagoides pteronyssinus (Dp) and to the native major allergens, Der p 1 and Der p 2, in sera from 18 adult patients (group A) with Dp-allergic asthma before ( t ₀) and 1, 2, 3, and 4 ( t ₁– t ₄) years after subcutaneous specific immunotherapy (SIT). A qualitative reduction ( P =0.05) of the IgE responses to Dp and Der p 2 was observed from t ₁ to t ₄, but a highly statistical significant decrease appeared at t ₃, ( P < 0.01). With regard to Der p 1 IgE values, the immunotherapy induced a significant decrease ( P < 0.01) at t ₃, but not before. In group A, the IgE responses to Der p 1 and Der p 2 were not correlated at t ₀ ( r _s=0.31; P = 0.2l) but were correlated at t₃ ( r _s= 0.78; P=0.001). We also examined sera from 14 adult patients (group B, same SIT schedule as group A) who were without respiratory symptoms at the end of the third year (t₃) of Dp SIT. At this time ( t ₃), there were no significant differences in Der p 1 and Der p 2 IgE levels between group A and group B.     

The association between atopy and asthma in a semirural area of Tanzania (East Africa)

BACKGROUND: Atopy is consistently associated with asthma, except in a study in Africa. We assessed the association between atopy and asthma in women from a semirural area of Tanzania (East Africa). METHODS: All pregnant women delivering at the district hospital during a 1-year period were recruited (n = 658, 60.6% of those selected). Asthma was investigated by a standard questionnaire and atopy by specific IgE (immunoglobulin E) antibodies to Dermatophagoides pteronyssinus (Der p 1) and cockroach. RESULTS: The prevalence of wheezing chest was 10.7%; of asthma, 3.5%. Levels of specific IgE of >0.35 kU/l (73%) and high levels of total IgE (62% higher than 1000 kU/l) were highly prevalent. Specific IgE antibody levels in sera were not associated with asthma (3.8% of women with negative specific IgE to any antigen had asthma in comparison to 4.0% of women with positive specific IgE; odds ratio [OR] = 1.06, 0.35-3.22). Total IgE was not different between women with asthma and women without asthma (P=0.36). CONCLUSIONS: In tropical regions, the association between allergy and asthma is complex, and specific IgE reactivity to environmental allergens may not be related to asthma.     

Asthma in Tanta, Egypt: serologic analysis of total and specific IgE antibody levels and their relationship to parasite infection.

The relationship between asthma, IgE and parasite infection was compared in 68 randomly selected patients with asthma and 37 nonasthmatic controls living in Tanta, Egypt. Sera were assayed for total IgE and for IgE antibodies to inhaled allergens (mite, cat, cockroach, ryegrass, ragweed and 3 fungi) and to parasite antigens (Schistosoma mansoni and Brugia malayi). Parasite infection was determined by microscopic examination of stool specimens. Total IgE levels were significantly higher in patients with asthma (geometric mean 909 IU/ml), than in controls (geometric mean 145 IU/ml, p less than 0.001). The high IgE levels correlated with parasite infection and the presence of IgE antibodies to S. mansoni antigens, which were also elevated compared to controls. The prevalence of allergen-specific IgE antibodies among Egyptian asthmatics was low by comparison with 'Western' asthmatics, but nonetheless higher than among Egyptian controls. A radioallergosorbent test (RAST) values of greater than 40 U/ml to any allergen was found in 19/68 (28%) sera from the asthma group, as compared to only 1/37 (3%) sera from controls (p less than 0.001). The highest RAST values were to dust mite (Dermatophagoides pteronyssinus and D. farinae) allergens, followed by rye grass and ragweed allergens. The results suggest that in this area of Egypt, several factors may influence the development of asthma, including nonspecific activation of IgE and/or inflammatory mechanisms by helminth parasites and sensitisation to environmental allergens.     

Correlates of sensitization to Blomia tropicalis and Dermatophagoides pteronyssinus in asthma in Barbados

BACKGROUND: Sensitivity to the mite Blomia tropicalis is related to asthma in tropical climates, but correlates of sensitivity to B. tropicalis and its relationship to Dermatophagoides pteronyssinus sensitivity have not been widely examined in families with asthma. The main objective of this study was to determine prevalence and correlates of sensitivity to these mites in families with asthma and characteristics of persons sensitized to both. METHODS: Antibodies to major antigens (Blo t 5 and Der p 1) of these mites were measured by immunochemiluminescent assay in 481 members of 29 families from Barbados ascertained through two asthmatic siblings. RESULTS: Blo t 5 sensitivity was present in 261 subjects (46%) and was associated with younger age, higher total serum IgE level, and more than a three-fold increased prevalence of asthma (42 vs. 13%). Der p 1 sensitivity was less common (27%) and showed similar associations with age, IgE, and asthma. Of the 261 subjects sensitized to Blo t 5, 116 were also sensitized to Der p 1; they were younger, had higher total and Blo t 5 specific IgE levels, and had more than twice the asthma prevalence as those sensitized to Blo t 5 alone (59 vs. 29%). Der p 1 sensitivity without Blo t 5 sensitivity was uncommon; 90% of those sensitized to Der p 1 were also sensitized to Blo t 5. Geometric mean total IgE levels were lowest in the 207 participants without any mite sensitization (102 U/ml), intermediate in 158 sensitized to either Blo t 5 OR Der p 1 (609 U/ml), and highest in 116 sensitized to both (1,869 U/ml). CONCLUSIONS: Blo t 5 is the predominant sensitizing mite allergen in these Barbadian families with correlates similar to Der p 1. Concomitant sensitization to Der p 1 appears to identify a more reactive subgroup of individuals at a higher risk of asthma.     

The synergistic effects of the IL-9 gene and environmental exposures on asthmatic Taiwanese families as determined by the transmission/disequilibrium test

Asthma occurs in genetically susceptible individuals in the presence of environmental factors. The interleukin-9 (IL-9) gene, one of the cytokine genes located on chromosome 5q31, plays an important role in the development of asthmatic syndrome by enhancing both T-cell and mast-cell function. This study investigated GT repeat polymorphism of the IL-9 gene and the gene-environment interactions, which may predispose individuals to asthma and atopy pathogenesis. In this study, we used the transmission/disequilibrium test (TDT) to investigate the relationship between asthma and the IL-9 gene by studying 123 parent-offspring trios and 91 siblings. For allele-specific TDT chi-squared test, allele 122 of the IL-9 gene showed significant association with asthmatics with specific IgE against house dust (HD) (P = 0.038). The additions of covariates to TDT to conduct the synergistic effects between the IL-9 gene and environmental factors into account were estimated by conditional logistic regression models. The odds ratio for transmission of allele 122 of the IL-9 gene was 1.23 (P = 0.28) for all asthmatic probands. There was slight increased interaction effect on asthma between transmission of allele 122 of IL-9 gene to offspring and who were exposed to the fur of pets (OR = 3.33, P = 0.047). We also detected elevated odds of transmission of allele 122 to atopic asthmatic probands (OR = 2.08, P = 0.03) and offspring with very high levels of serum IgE (> or = 800 IU mL(-1)). In conclusion, this study has found that the IL-9 gene was slightly associated with asthmatics who have positive specific IgE against Der p (or Der f) and house dust, when information on environmental factors was incorporated as effect modifiers.     

Quantitative measurement of IgE antibodies to purified allergens using streptavidin linked to a high-capacity solid phase

BACKGROUND: Commercially available assays for IgE antibody provide results in international units per milliliter for many allergen extracts, but this is not easily achieved with purified or novel allergens. OBJECTIVE: To develop assays for IgE antibody suitable for purified or novel allergens by using a commercially available immunosorbent. METHODS: Streptavidin coupled to a high-capacity immunosorbent (CAP) was used to bind biotinylated purified allergens from mite (Der p 1 and Der p 2), cat (Fel d 1), and dog (Can f 1). Assays for IgE antibody to these allergens were performed on sera from children (asthma and control) as well as adults with atopic dermatitis. RESULTS: The results were validated by serial dilution of sera with high and low levels of IgE antibody and were quantitated in international units per milliliter by using a standard curve. Values for IgE antibody to Der p 1, Der p 2, and Fel d 1 correlated with values obtained with the allergen extracts (r2 = 0.80, 0.84, and 0.95, respectively; P < .001 in each case). Furthermore, the values for IgE antibody in sera from children with high exposure to mite and cat allergens demonstrated 10-fold higher levels of IgE antibody to Der p 1 and Der p 2 than to Fel d 1 (P < .001). CONCLUSION: The streptavidin immunosorbent technique provides a new method for quantifying IgE antibody to purified proteins. The results provide evidence about the high quantities of IgE antibody to purified inhalant allergens in patients with atopic dermatitis. In addition, the results demonstrate major differences in IgE antibodies specific for mite and cat allergens among children with high exposure to both allergens.     

Indoor mite allergens in patients with respiratory allergy living in Porto, Portugal

We investigated the levels of mite allergens (Der p 1, Der f 1, Der 2, and Lep d 1) in dust samples from the homes of 59 patients with asthma, 36 sensitized to house-dust mites (HDM) and 23 to grass pollen (controls), living in Porto, northern Portugal. The relationship between exposure and sensitization to HDM and the influence of housing conditions on mite-allergen levels were also evaluated. Der p 1 (median 9.2 μg/g) and Der 2 (4.6 μg/g) were the main allergens, while Der f 1 and Lep d 1 levels were always <1 μg/g dust and undetectable in 11% and 47% of samples, respectively. All HDM-sensitized asthmatics were exposed to Der p 1 levels >2 μg/g and their homes contained significantly higher levels of Der p 1 (median 12.5 vs 6.4 μg/g; P=0.008) and Der 2 (6.2 vs 3.0 μg/g; P=0.004) when compared to the control group. A significant correlation was observed between the exposure to Der p 1 and the wheal area at skin testing with the Dermatophagoides pteronyssinus (Dp) extract (P=0.01) as well as with serum specific IgE levels to Dp (P=0.03). Patients with higher levels of serum specific IgE (≥17.5 HRU/ml) were also more frequently exposed to Der p 1 levels ≥10 (μg/g (P=0.002). Old homes, presence of carpets, and signs of dampness were conditions associated with significantly higher levels of mite allergens. In conclusion, we found high levels of Der p 1 and Der 2 particularly in the homes of HDM-sensitized patients and we confirm the relationship between exposure and sensitization to HDM, assessed by both in vivo and in vitro methods. In addition to a favorable outdoor climate, we found in our region housing conditions propitious to mite growth, suggesting that specific geographic characteristics must also be taken into account for the correct planning of mite-avoidance measures.     

Studies on IgG subclass antibodies in adult asthma. 1. Serum antigen specific IgG subclass antibodies in asthmatics with late asthmatic response

It is clear that immediate asthmatic response is mediated by IgE-dependent mechanisms. However, late asthmatic response is induced by inhalation of antigens without antigen specific IgE antibodies in some asthmatics, especially in intractable asthma induced by Candida antigen. To elucidate the relationship between those bronchial responses and antibodies, antigen specific IgG subclass antibodies in sera from asthmatics were measured and compared with IgE antibody. The results were as follows. 1. Avidin-biotin ELISA (enzyme-linked immunosorbent assay) method was established for the measurement of specific IgG and IgG subclass antibodies to mite or Candida antigen. 2. Serum levels of antigen specific IgG and IgG1 antibodies in asthmatics with LAR provoked by mite or Candida antigen were significantly higher than those in asthmatics without LAR (p less than 0.01). 3. Serum levels of specific IgE antibody to these antigens in asthmatics with LAR provoked by mite or Candida antigen were slightly lower than those in asthmatics without LAR, though the difference is not significant. These results suggest that high serum levels of specific IgG and IgG1 antibodies to these antigens play a role in inducing LAR in asthmatics with LAR.     

Prevalence of specific IgE antibodies against piperazine in employees of a chemical plant

In 5 out of 72 (7%) workers exposed to the asthma-inducing amine piperazine, specific IgE antibodies against a conjugate between human serum albumin and piperazine were demonstrated with RAST and RAST inhibition techniques. No specific antibodies were found in 64 nonexposed workers at the same plant, and in 60 healthy reference subjects. Eight out of the 72 (11%) exposed employees had unequivocal histories of piperazine-associated asthma, but only 4 of them had specific IgE antibodies against piperazine. However, there was a statistically significant association between specific antibodies and disease, as 4 out of 5 RAST-positive subjects were asthmatics, as compared with 4 out of the 67 RAST-negatives (p = 0.0003). The 4 RAST-positive asthmatics had been exposed to piperazine for between 6 and 168 months before their asthma started, as compared with induction times of less than a month for the 4 RAST-negatives. This discrepancy may reflect different pathogeneses for piperazine-associated asthma; either type-I allergy, pseudo-allergic reactivity or nonspecific irritative effect on the bronchi. The RAST-positive subjects did not differ from other employees as regards smoking habits but had significantly elevated levels of total serum IgE (p = 0.004).     

A sensitive reverse ELISA for the measurement of specific IgE to Der p 2, a major Dermatophagoides pteronyssinus allergen.

BACKGROUND: Epidemiologic studies have shown that the presence of IgE antibodies to house dust mite and other indoor allergens is an important risk factor for asthma. OBJECTIVE: The aim of this study was to develop a reverse ELISA (rELISA) for measuring specific IgE to Der p 2, a major Dermatophagoides pteronyssinus (Dpt) allergen, as a potential tool for followup of allergen immunotherapy. METHODS: Recombinant Der p 2 allergen or a monoclonal antibody to Der p 2 was used to coat plates in conventional ELISA (cELISA) and rELISA, respectively. Sera from 48 asthmatic patients with positive skin prick test (SPT+) to D. pteronyssinus extract were analyzed for total IgE and specific IgE to Der p 2, and the results were compared with a group of 41 SPT asthmatic and 30 SPT- control subjects. RESULTS: The sensitivity of the two assays for Der p 2-specific IgE was 3.9 EU/mL and their specificities were confirmed by inhibition tests, in a dose-dependent manner. There was a significant positive correlation between cELISA and rELISA (r = 0.74; P < 0.0001). However, rELISA was more sensitive than was cELISA, regarding both the positive sera percentage (70.8% vs 52.1%) and the Der p 2-specific IgE levels (28.4 vs 4.5 EU/mL) in SPT+ asthmatic patients. CONCLUSIONS: rELISA has shown to be a sensitive and alternative method for measuring Der p 2-specific IgE without using radioactive techniques. Detection of specific IgE to major allergens and relevant peptides, and identification of B cell epitopes in allergens will provide valuable information for the design of allergen analogs and peptides for immunotherapy.     

Association between quantitative traits underlying asthma and the HLA-DRB1 locus in a family-based population sample

The region of human chromosome 6 containing the MHC has been identified as influencing asthma and atopy (allergy) by several genome-wide searches. The MHC contains many genes with potential effects on innate and specific immunity. As a first step in dissecting MHC influences on asthma and its underlying quantitative phenotypes, we have examined the HLA-DRB1 locus in a population sample consisting of 1004 individuals from 230 families from the rural Australian town of Busselton. The locus was strongly associated with the (log(e)) total serum IgE concentration, accounting for 4.0% of the sigma(2) (variance) in that trait (multi-allelic test, P=0.00001). The locus also influenced specific IgE titres to common allergens (multi-allelic tests, 2.8% sigma(2) for the house dust mite allergen Der p I, P=0.0013; 3.0% of sigma(2) for Der p II, P=0.0007; and 2.1% of sigma(2) for the cat allergen Fel d I, P=0.014). No associations were found to the categorical phenotype of asthma, or to the quantitative traits of peripheral blood eosinophil counts and bronchial hyper-responsiveness. Transmission disequilibrium tests excluded genetic admixture as a cause of false-positive findings. The results indicate that HLA-DRB1 alleles modulate the total serum IgE concentration and IgE responses to allergens, but do not account for the previous observations of linkage of asthma to the MHC.     

Differences in titres of IgE, IgG4 and other IgG subclass anti- Der p 2 antibodies in allergic and non-allergic patients measured with recombinant allergen

Background The mite allergens are recognized as major causes of allergic disease such as bronchial asthma, allergic rhinitis and atopic dermatitis. The functions of allergen-specific IgG subclass antibodies are not defined.
Objective In order to clarify the relationship between IgE and IgG subclasses, we examined scrum levels of the Dermatophagoides pteronyssisus group 2 (Der p 2)-specific antibodies of IgH. IgG total and IgG subclasses in children with mite allergy.
Methods We prepared a recombinant Der p 2 fusion protein and examined serum levels of Der p 2 antigen-specific antibodies by enzyme-linked immunosorbent assay (FLISA) systems developed in our laboratory using a recombinant Der p 2 as target antigen. Sera from 240 children with mite allergy and 25 controls were measured.
Results The serum levels of specific IgE and, to lesser degree, lgG4 were higher in allergic children than non-allergic controls, while in the levels of the other IgG subclasses there was no difference between the two groups. There was no correlation between levels of specific IgF and IgG4 or in those between specific IgG4 and other IgG subclasses.
Conclusion Results indicate that the induction of Der p 2-specific lgG4 in allergic diseases is independent to IgE as well as other IgG subclasses.     

Studies on IgG subclass antibodies in adult asthma. 2. Changes in serum antigen specific IgG subclass antibodies for aging and intractability in asthmatics]

To clarify the factors which induce intractable asthma, the level of serum IgG subclass antibodies to mite (Dermatophagoides farinae) and Candida antigens (Candida albicans) for aging and severity was investigated in 230 bronchial asthmatics (Male: 117, Female: 113) aged 6-81 years old (mean age = 40). Total IgE level and IgE antibodies to mite and Candida antigens were measured by radioimmunosorbent test (RIST) and radioallergosorbent test (RAST), respectively. The serum level of IgG and IgG1 antibodies to the antigens were measured by enzyme-linked immunosorbent assay (ELISA). The results were as follows: 1) The incidence of severe asthma in aged and late onset asthmatics, especially late onset intractable asthma (LOIA), was higher than that in young and early onset asthmatics. 2) The serum level of total IgE and IgE antibodies to mite in aged and late onset asthmatics was lower than that in young and early onset asthmatics. 3) The incidence of severe and intractable asthmatics in the group of low IgE levels (less than 300 IU/ml) was higher than that in the group of high IgE levels (over 500 IU/ml). The incidence of positive IgE (RAST) score to mite in severe and intractable asthmatics was lower than that in mild and moderate asthmatics. 4) Considering aging, the serum levels of IgG and IgG1 antibodies to mite and Candida in severe and intractable asthmatics was higher than those in mild asthmatics. These data indicate that the aged and late onset asthmatics may produce dominantly the IgG (IgG1) antibody to the antigens, and have severe asthma attacks caused by IgG (IgG1) rather than IgE antibody.     

Exposure to house-dust mite allergen (Der p I) and the development of asthma in childhood. A prospective study

BACKGROUND AND METHODS. Children with asthma commonly have positive skin tests for inhaled allergens, and in the United Kingdom the majority of older children with asthma are sensitized to the house-dust mite. In a cohort of British children at risk for allergic disease because of family history, we investigated prospectively from 1978 to 1989 the relation between exposure to the house-dust mite allergen (Der p I) and the development of sensitization and asthma. RESULTS. Of the 67 children studied in 1989, 35 were atopic (positive skin tests), and 32 were nonatopic. Of the 17 with active asthma, 16 were atopic (P less than 0.005), all of whom were sensitized to the house-dust mite, as judged by positive skin tests and levels of specific IgE antibodies (P less than 0.001). For house-dust samples collected from the homes of 59 of the children in 1979 and from 65 homes in 1989, the geometric means for the highest Der p I exposure were, respectively, 16.1 and 16.8 micrograms per gram of sieved dust. There was a trend toward an increasing degree of sensitization at the age of 11 with greater exposure at the age of 1 (P = 0.062). All but one of the children with asthma at the age of 11 had been exposed at 1 year of age to more than 10 micrograms of Der p I per gram of dust; for this exposure, the relative risk of asthma was 4.8 (P = 0.05). The age at which the first episode of wheezing occurred was inversely related to the level of exposure at the age of 1 for all children (P = 0.015), but especially for the atopic children (r = -0.66, P = 0.001). CONCLUSIONS. In addition to genetic factors, exposure in early childhood to house-dust mite allergens is an important determinant of the subsequent development of asthma.     

Prevalence of Blomia tropicalis in wheezing children in central Taiwan.

BACKGROUND AND PURPOSE: In a previous study, we found that wheezing children in rural central Taiwan had a significantly lower average sensitization rate to Dermatophagoides pteronyssinus (Der p) than those in Taipei city. We propose that Blomia tropicalis (Blo t) might be the major mite allergen in rural central Taiwan. METHODS: Using the preserved sera from our previous study, we retrospectively measured specific immunoglobulin E (IgE) antibody to Blo t and analyzed the correlation between Blo t and Der p in wheezing children in rural central Taiwan. A total of 2206 children with physician-diagnosed asthma and wheezing were enrolled and categorized among five age groups. The sensitization rate and level of specific IgE antibody to Blo t were analyzed. RESULTS: The age-specific sensitization rates and the level of specific IgE antibody to either Blo t or Der p increased progressively with increasing age, being greatest in the age group 8 to 12 years. A significant positive correlation existed between sensitization rate and age for both Blo t and Der p (p=0.001). Specific IgE antibody to Blo t was undetectable in patients younger than 1.5 years. A significant positive correlation also existed between age and anti-Blo t IgE antibody level (p<0.003). However, the allergen-specific IgE level was lower for Blo t than Der p (p<0.005) in all age groups. CONCLUSIONS: Blo t might be the major mite allergen to associated with early wheeze and atopic asthma in rural central Taiwan.     

House dust mite-specific IgE antibodies in induced sputum are associated with sputum eosinophilia in mite-sensitive asthmatics.

BACKGROUND: Although allergen-specific IgE antibodies have been considered to play an important role in the pathogenesis of atopic asthma, the role of IgE antibodies in the development of airway inflammation is not well defined. OBJECTIVE: To evaluate the association between allergen-specific IgE antibodies and inflammation of the asthmatic airway. METHODS: We measured house dust mite (HDM; Dermatophagoides farinae)-specific IgE antibodies in both serum and induced sputum from 16 HDM-sensitive asthmatic patients, and evaluated their association with sputum eosinophilia and eosinophil cationic protein (ECP) levels in induced sputum. RESULTS: Levels of HDM-specific IgE antibodies in induced sputum were significantly higher in asthmatic patients than in controls (P < .01). In asthmatic patients, levels of HDM-specific IgE antibodies were significantly higher in induced sputum samples with eosinophilia (sputum eosinophil count > or = 5% of 200 counted non-squamous cells) than in those without eosinophilia (P < .05). There were no significant differences in serum levels of HDM-specific IgE antibodies between asthmatic patients with sputum eosinophilia and asthmatic patients without sputum eosinophilia. In asthmatic patients, sputum ECP levels were significantly correlated with levels of HDM-specific IgE antibodies (r = 0.60, P = .01) in induced sputum but not with those in serum. CONCLUSION: We conclude that allergen-specific IgE antibodies in induced sputum from atopic asthmatics are associated with sputum eosinophilia. This result suggests that IgE-dependent mechanisms are involved in eosinophilic inflammation of the airway in atopic asthmatics.     

Association of tumor necrosis factor polymorphisms with asthma and serum total IgE

Tumor necrosis factors (TNF; TNFA and TNFB) are major pro-inflammatory cytokines that are thought to be important in the pathogenesis of asthma. However, the functions of genetic polymorphisms in these cytokines have not been thoroughly examined in the context of asthma pathology. In an effort to discover polymorphism(s) in genes whose variant(s) have been implicated in asthma phenotypes, we examined the genetic effects of TNF (TNFA and TNFB) polymorphisms on asthma and total serum IgE level. Seven common single-nucleotide polymorphisms (SNP) in TNF genes were genotyped in a Korean asthma cohort (asthmatics n=550, normal controls n=171). Six common haplotypes could be constructed in the TNF gene cluster due to very strong LD between TNFA and TNFB, located 13 kb apart on chromosome 6p21. One SNP (TNFA-308G>A) showed a significant association with the risk of asthma (P=0.0004). The frequency of TNFA-308A allele-containing genotype in asthmatics (9.8%) was much lower than that in normal controls (22.9%). The protective effects of this polymorphism on asthma were also evident in separated subgroups by atopic status (P=0.05 in non-atopic subjects and P=0.003 in atopic subjects). The most common haplotype of the TNF gene (TNF-ht1[GGTCCGG]) was associated with total serum IgE (immunoglobulin E) levels in asthma patients, especially in non-atopic patients (P=0.004). Genetic variants of TNF might be involved in development of asthma and total serum IgE level in bronchial asthma patients. The results of this study could be helpful to understand the function of important TNF genes in asthma and IgE production.     

Allergy to dermatophagoides in a group of Spanish gypsies: genetic restrictions

BACKGROUND: Spanish gypsies have traditionally lived as nomads, a reason why few epidemiological studies were done in this ethnic group. However, the high prevalence of asthmatic diseases demonstrated in a population residing in the North of Spain induces us to analyse whether it was due to the influence of genetic loci previously implicated in other population studies as causing the disorders. METHODS: DRB1* and DQB1* HLA class II, TCR-Valpha8.1, FcepsilonRI-beta Rsa I exon 7 and intron 2, TNF-beta (LTalpha-Nco I) and CD14, were tested for association with asthma and atopy by multiple regression analysis, in 5 families comprising 87 individuals. RESULTS: Significant associations were found with DQB1*02 (p = 0.02) and DQB1*0301 (p = 0.008) and elevated levels of total serum IgE. A negative association (p = 0.02) was found between total serum IgE and DRB1*14. FcepsilonRI-beta Rsa I-In2 allele 1 was associated with high levels of total serum IgE (p = 0.04). Levels of Der p 1 IgE antibodies were negatively associated with DRB1*11-DQB1*0301 (p = 0.007), and positively with TCR Valpha-8 allele 1 (p = 0.04) and with FcepsilonRI-beta Rsa I-In2 allele 1 (p = 0.009). CONCLUSIONS: Our results do not show any association between asthma and the genetic loci studied although they do suggest the existence of multiple genetic influences on the allergic response in these families.