Mite-sensitized Children Research Articles

Mite allergen sensitization patterns in Turkish children: Age-related changes and molecular correlations.

Mites are ubiquitous aeroallergens found worldwide. Elucidating individual mite allergen sensitization patterns provides critical insights for managing allergic diseases. This study aimed to investigate molecular allergen (MA) sensitization patterns across different age groups and explore cluster relationships among mite-sensitized children. We analyzed 76 children who exhibited sensitization to at least one of the 17 distinct mite MAs through microarray testing. Dermatophagoides farinae exhibited a slightly higher prevalence of sensitization compared with Dermatophagoides pteronyssinus. Der p 1/2 and Der f 1/2 demonstrated an almost 40% sensitization rate, while Der p 10/Blo t 10, Der p 20, Der p 23, and Gly d 2/Lep d 2 displayed an approximately 20% sensitization rate. Sensitization levels and ratios increased significantly with age for Der p 23 but showed numerical rises for other MAs, except for Der p 10/Blo t 10. The presence of various types of atopic diseases had only a minimal impact on sensitization profiles. Strong correlations emerged between Der f 2 and Der p 2, Der p 10 and Blo t 10, Der p 21 and Blo t 5, as well as Gly d 2 and Lep d 2. Hierarchical cluster analysis substantiated these relationships. Der p 10 and its homolog Blo t 10-sensitive patients (15/76) were mostly seen as mono sensitization(12/15). Ten patients exhibited monosensitization to Der p 20, suggesting a possible association with scabies infection. In children, mite sensitization diversity and levels increased with age. The presence of significant correlations/cluster relationships among these sensitizations underscores homologies among specific MAs.

Cross-talk between airway and gut microbiome links to IgE responses to house dust mites in childhood airway allergies

A connection between airway and gut microbiota related to allergen exposure in childhood allergies was not well addressed. We aimed to identify the microbiota alterations in the airway and gut related to mite-specific IgE responses in young children with airway allergies. This study enrolled 60 children, including 38 mite-sensitized children (20 rhinitis and 18 asthma), and 22 non-mite-sensitized healthy controls. Microbiome composition analysis of the throat swab and stool samples was performed using bacterial 16S rRNA sequencing. An integrative analysis of the airway and stool microbial profiling associated with IgE reactions in childhood allergic rhinitis and asthma was examined. The Chao1 and Shannon indices in the airway were significantly lower than those in the stool. Additionally, an inverse association of the airway microbial diversity with house dust mite (HDM) sensitization and allergic airway diseases was noted. Fecal IgE levels were positively correlated with the serum Dermatophagoides pteronyssinus- and Dermatophagoides farinae-specific IgE levels. Airway Leptotrichia spp. related to asthma were strongly correlated with fecal Dorea and Ruminococcus spp., which were inversely associated with fecal IgE levels and risk of allergic rhinitis. Moreover, four airway genera, Campylobacter, Selenomonas, Tannerella, and Atopobium, were negatively correlated with both serum mite-specific and fecal IgE levels. Among them, the airway Selenomonas and Atopobium spp. were positively correlated with stool Blautia and Dorea spp. related to asthma and allergic rhinitis, respectively. In conclusion, airway microbial dysbiosis in response to HDM and its cross-talk with the gut microbial community is related to allergic airway diseases in early childhood.

Airway Microbial Diversity is Inversely Associated with Mite-Sensitized Rhinitis and Asthma in Early Childhood

Microbiota plays an important role in regulating immune responses associated with atopic diseases. We sought to evaluate relationships among airway microbiota, serum IgE levels, allergic sensitization and their relevance to rhinitis and asthma. Microbial characterization was performed using Illumina-based 16S rRNA gene sequencing of 87 throat swabs collected from children with asthma (n = 32) and rhinitis (n = 23), and from healthy controls (n = 32). Data analysis was performed using QIIME (Quantitative Insights Into Microbial Ecology) v1.8. Significantly higher abundance of Proteobacteria was found in children with rhinitis than in the healthy controls (20.1% vs. 16.1%, P = 0.009). Bacterial species richness (Chao1 index) and diversity (Shannon index) were significantly reduced in children with mite sensitization but not in those with food or IgE sensitization. Compared with healthy children without mite sensitization, the mite-sensitized children with rhinitis and asthma showed significantly lower Chao1 and Shannon indices. Moraxella and Leptotrichia species were significantly found in the interaction of mite sensitization with rhinitis and asthma respectively. Airway microbial diversity appears to be inversely associated with sensitization to house dust mites. A modulation between airway dysbiosis and responses to allergens may potentially cause susceptibility to rhinitis and asthma in early childhood.

Preventing Severe Asthma Exacerbations in Children. A Randomized Trial of Mite-Impermeable Bedcovers.

Allergen exposure in sensitized individuals with asthma interacts with viruses to increase the risk of asthma exacerbation. To evaluate the use of house dust mite-impermeable bedding and its impact on severe asthma exacerbations in children. We randomized mite-sensitized children with asthma (ages 3-17 yr) after an emergency hospital attendance with an asthma exacerbation to receive mite-impermeable (active group) or control (placebo group) bed encasings. Over a 12-month intervention period, the occurrence of severe asthma exacerbations was investigated. Of 434 children with asthma who consented, 286 (mean age, 7.7 yr; male sex, 65.8%) were mite sensitized, and 284 were randomized (146 to the active group and 138 to the placebo group). At 12 months, significantly fewer children in the active group than in the placebo group had attended the hospital with an exacerbation (36 [29.3%] of 123 vs. 49 [41.5%] of 118; P = 0.047). In the multivariable analysis, the risk of emergency hospital attendance was 45% lower in the active group (hazard ratio, 0.55; 95% confidence interval [CI], 0.36-0.85; P = 0.006) than in the placebo group. The annual rate of emergency hospital attendance with exacerbations was 27% lower in the active group than in the placebo group, but this did not reach significance (estimated marginal mean [95% CI], active, 0.38 [0.26-0.56] vs. placebo, 0.52 [0.35-0.76]; P = 0.18). No difference between the groups in the risk of prednisolone use for exacerbation was found (hazard ratio, 0.82; 95% CI, 0.58-1.17; P = 0.28). Mite-impermeable encasings are effective in reducing the number of mite-sensitized children with asthma attending the hospital with asthma exacerbations but not the number requiring oral prednisolone. This simple measure may reduce the health care burden of asthma exacerbations in children. Clinical trial registered with www.isrctn.com (ISRCTN 69543196).

Efficacy of Nasal Cellulose Powder in the Symptomatic Treatment of Allergic Rhinitis: A Randomized, Double-Blind, Placebo-Controlled Trial.

PurposeNasal Cellulose Powder (NCP), which can prevent from binding an allergen to nasal mucosa, may reduce allergic rhinitis (AR) symptoms in dust mite-sensitized children. This study was conducted to assess the efficacy of NCP in improving clinical symptoms of a nasal airflow limitation and the response of nasal inflammatory cells.MethodsChildren with dust mite-sensitized AR aged 6-18 years were recruited. After a 4-week run-in period, NCP or a placebo was administered, 1 puff per nostril 3 times daily for 4 weeks. The nasal provocation test (NPT) with Dermatophagoides pteronyssinus (Der p) was performed before and after treatment. The daily symptom scores (DSS), daily medication scores (DMS), the peak nasal inspiratory flows (PNIF), nasal airway resistance (NAR), as well as the maximum tolerated dose of NPT and eosinophil counts in nasal scraping, were evaluated.ResultsSixty children (30 NCP and 30 placebos) were enrolled. Before treatment, there were no significant differences in age, dust mite control measures, DSS, DMS, PNIF, NAR, the maximum tolerated dose of NPT, or nasal eosinophil scores between children receiving NCP and placebos. After treatment, there were no significant differences between the NCP and placebo groups in the median (range) of the outcomes—DSS: 2.06 (0.18-3.77) vs 1.79 (0.08-7.79), P=0.756; DMS: 1.60 (0-5.13) vs 0.56 (0-4.84), P=0.239; PNIF (L/min): 110 (60-160) vs 100 (50-180), P=0.870; NAR (Pa/cm3/s): 0.40 (0.20-0.97) vs 0.39 (0.24-1.32), P=0.690; the maximum tolerated dose of NPT and the nasal eosinophil scores: 1 (0-4) vs 1 (0-4), P=0.861.ConclusionsNCP treatment may not be more effective than placebo treatment in dust mite-sensitized AR children.

Risk factors, lung function and bronchial hyperresponsiveness in current dust mite-induced allergic rhinitis

Purpose: We analyzed the pulmonary function and risk factors of allergic rhinitis (AR) in dust mite-sensitized children with current AR and no history of asthma. Methods: In this cross-sectional study, demographic and disease-related information was obtained from 1,792 Korean children aged 9?12 years using a questionnaire, skin-prick testing, spirometric analysis, and methacholine challenge testing. Results: A total of 672 children were analyzed. The control group consisted of 583 children without any allergic diseases who were not sensitized to 16 common allergens. The group with current AR and dust mite sensitization consisted of 89 children. Binary logistic regression analysis showed that helminth infection (adjusted odds ratio [aOR], 2.88; 95% confidence interval [CI], 1.23?6.77) and antibiotic use during infancy (aOR, 1.89; 95% CI, 1.10?3.25) were the risk factors. Pet ownership (aOR, 0.32; 95% CI, 0.15?0.69) and older siblings (aOR, 0.58; 95% CI, 0.35?0.96) were protective factors. Spirometry results did not differ between the control and dust mite-induced AR groups. None of the children showed a bronchodilator response. However, 8.5%, 7.1%, and 2.1% of the control-group children and 28.7%, 23.0%, and 8.0% of the dust mite-induced AR-group children showed methacholine PC20 (provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second) values of ≤25 mg/mL, ≤16 mg/mL, and ≤8 mg/mL, respectively (P<0.01). Conclusion: The prevalence of current dust mite-induced AR may be reduced by controlling environmental factors. Even though the spirometry results seemed to be normal, bronchial hyperresponsiveness occurred more frequently in children with dust mite-induced AR than in normal children.

Distinguishing benign from pathologic TH2 immunity in atopic children

Although most children with asthma and rhinitis are sensitized to aeroallergens, only a minority of sensitized children are symptomatic, implying the underlying operation of efficient anti-inflammatory control mechanisms. We sought to identify endogenous control mechanisms that attenuate expression of IgE-associated responsiveness to aeroallergens in sensitized children. In 3 independent population samples we analyzed relationships between aeroallergen-specific IgE and corresponding allergen-specific IgG (sIgG) and associated immunophenotypes in atopic children and susceptibility to asthma and rhinitis, focusing on responses to house dust mite and grass. Among mite-sensitized children across all populations and at different ages, house dust mite-specific IgG/IgE ratios (but not IgG4/IgE ratios) were significantly lower in children with asthma compared with ratios in those without asthma and lowest among the most severely symptomatic. This finding was mirrored by relationships between rhinitis and antibody responses to grass. Depending on age/allergen specificity, 20% to 40% of children with allergen-specific IgE (sIgE) of 0.35 kU/L or greater had negative skin test responses, and these children also expressed the high sIgG/sIgE immunophenotype. sIgG1 from these children inhibited allergen-induced IgE-dependent basophil activation in a dose-dependent fashion. Profiling of aeroallergen-specific CD4(+) TH memory responses revealed positive associations between sIgG/sIgE ratios and IL-10-dependent gene signatures and significantly higher IL-10/TH2 cytokine (protein) ratios among nonsymptomatic children. In addition to its role in blocking TH2 effector activation in the late-phase allergic response, IL-10 is a known IgG1 switch factor. We posit that its production during allergen-induced memory responses contributes significantly to attenuation of inflammation through promoting IgG1-mediated damping of the FcεRI-dependent acute-phase reaction. sIgG1/sIgE balance might represent a readily accessible therapeutic target for asthma/rhinitis control.

Efficacy of an in-home test kit in reducing dust mite allergen levels: results of a randomized controlled pilot study

Background: Dust mite allergens can induce allergic sensitization and exacerbate asthma symptoms. Although dust mite reduction and control strategies exist, few asthmatics employ them. Objectives: We examined whether an in-home test kit, which quantifies dust mite allergen levels, resulted in behavioral changes in implementation and maintenance of mite reduction strategies and helped reduce allergen levels in homes of dust mite-sensitive children. Methods: We enrolled 60 households of children aged 5–15 with parent-reported dust mite allergy into a randomized controlled trial. Intervention homes (N = 30) received educational material about reducing dust mites and test kits at 1, 2, 5 and 8 months. Control homes (N = 30) received only educational material. At baseline, 6 and 12 months, study staff visited all homes, collected dust samples from three locations and obtained information about parents’ mite reduction behaviors by questionnaire. Allergen concentrations (Der f 2/Der p2) in dust were assessed by immunoassays. After adjusting for visit and location, allergen concentrations in intervention and control homes were compared using mixed effects model analysis. Results: In the intervention homes, allergen concentrations in the child’s bedroom and living room floors were significantly reduced over time compared to control homes. Although not all location-specific differences in allergen concentrations were statistically significant, combining data across locations, there was a differential reduction in allergen concentrations in the intervention group versus the control group (p = 0.02). Conclusion: The use of in-home test kits along with education may beneficially influence behaviors and attitudes toward dust mite reduction strategies and help reduce residential dust mite allergen levels.

Sublingual immunotherapy in mite-sensitized children with atopic dermatitis: a randomized, open, parallel-group study

Sublingual immunotherapy in mite-sensitized children with atopic dermatitis: a randomized, open, parallel-group study

Two year follow-up of clinical and inflammation parameters in children monosensitized to mites undergoing subcutaneous and sublingual immunotherapy

Both SCIT (subcutaneous immunotherapy) and SLIT (sublingual immunotherapy) have clinical and immunologic efficacy in children with rhinitis and asthma but comparative studies are scarce. To investigate the clinical and immunological efficacy of mite-specific SLIT and SCIT in children with rhinitis and asthma. Thirty children monosensitized to house dust mite were randomized to receive either active SCIT or SLIT or placebo for 1 yr in a double-blind double-dummy placebo controlled design (Yukselen A et al., Int Arch Allergy Immunol 2012; 157:288-298). Thereafter, the placebo group was randomized to receive SCIT or SLIT, and for 1 yr all patients received active treatment with SCIT or SLIT. Symptom scores, drug usage, titrated skin prick tests, nasal and bronchial allergen provocation doses, serum house dust mite-specific immunglobulin E, sIgG4, IL-10 and IFN- g levels were evaluated. The reduction of clinical scores with SLIT was more evident after 2 years of treatment in comparison to both the baseline and DBPC phase of the study. The change in titrated skin prick tests and nasal provocative doses was more prominent with both SCIT and SLIT at the end of the open phase. Although the increase inbronchial provocative doses was not significant at the end of the first year of treatment with SLIT, it reached a statistically significant difference after two years of treatment. The clinical efficacy of SLIT is more prominent at the end of the second year, although this improvement is observed from the first year of treatment with SCIT in mite-sensitive children.

The Effect of Specific Immunotherapy on Natural Killer T cells in Peripheral Blood of House Dust Mite-Sensitized Children with Asthma

To investigate the effects of specific immunotherapy on the NKT cells in peripheral blood and the ability of NKT cells to proliferate in response to alpha-galactosylceramide (alpha-GalCer) in house-dust-mite- (HDM-) sensitized asthma children, peripheral blood mononuclear cells were isolated from 42 asthmatic children, of whom 24 were on specific immunotherapy (SIT) for more than a year and 20 were healthy. Compared with control group, the ratio of peripheral blood NKT and CD4+NKT cells was significantly decreased (P < 0.01) and was elevated in SIT asthma group (P < 0.05), respectively, but it was still less than the normal control group (P < 0.01). The level of IL-4 in serum secreted by NKT cells in asthma group was significantly higher than that of control group (P < 0.01), particularly apparent after 72 hours. The level of IL-4 in SIT group decreased significantly (P < 0.01). The level of IL-10 in serum secreted by NKT cells in asthma group was decreased significantly than that of the control group (P < 0.01) especially in 48 hours, while that of SIT group was increased significantly (P < 0.01). These results suggest that the pathogenesis of asthma may be related to the ratio and dysfunction of NKT and CD4+NKT cells.

Sensitization of Children to Storage Mites in Kutahya, Turkey

Specific IgE against Acarus siro, Glycphagus domesticus, Tyrophagus putrescentiae, and Lepidoglyphus destructor have been investigated by ELISA in sera of 92 children. Of them, 41 were found to be specific IgE positive (> or = 0.35 IU/ml) against at least one of house dust mite species, Dermatophagoides pteronyssinus and Dermatophagoides farinae, by an immunoblot. In 65.9% of the dust mite-sensitized children, specific IgE against at least one of these mite species was found. Sensitization levels, including co-sensitization cases were found to be 35.7% against A. siro, 24.4% against T. putrescentiae, 31.7% against L. destructor, and 26.8% against G. domesticus. In non-sensitized children, dust mite sensitization level was found to be 25.5%. Breakdown of sensitization by individual species in this group was; against A. siro and T. putrescentiae at 7.8%, against L. destructor at 13.7%, and against G. domesticus at 9.8%. When all children were reckoned, 43.5% was found to be sensitized against at least one storage mite species, with sensitizations against A. siro at 18.5%, T. putrescentiae at 26.1%, L. destructor at 21.7%, and G. domesticus at 17.4%. In dust samples collected from the dwellings of children, distribution of species was found to be A. siro (17%), G. domesticus (23%), T. putrescentiae (29%), L. destructor (25%), and unidentified (6%). In Fisher's chi-square test on SPSS program, there was a relationship between dust mite sensitization and storage mite sensitization (P < 0.05), but no meaningful relationship was found on the basis of individual mite species.

Indices of lower airway inflammation in children monosensitized to house dust mite after nasal allergen challenge

There are few available data assessing the united airway disease and its systemic aspects in children. With this study, we aimed to investigate the inflammation markers of upper and lower airways before and after nasal allergen challenge in mite sensitive children with different clinical expression of the allergic disease. Four study groups were formed: rhinitis only, without bronchial hyper-responsiveness (R, n = 10), rhinitis with asthma (R + A, n = 22), atopic asymptomatics (AA, n = 8) and nonallergic healthy controls (C, n = 10). Blood eosinophils, nasal and sputum eosinophils, sputum eosinophil cationic protein (ECP) and cys-LTs, and serum ECP levels were measured before and 24 h after nasal allergen challenge. The groups were comparable in terms of age and gender. Cumulative symptom scores recorded during and 1 h after nasal challenge were not significantly different between patients with R, R + A and AA groups. At T(24), the children belonging to R, R + A and AA showed significant increases in nasal eosinophils (P < 0.01, P < 0.001, and P = 0.01, respectively), sputum eosinophils (P = 0.01, P < 0.001, and P < 0.05, respectively) and blood eosinophils (P < 0.01, P < 0.001, and P < 0.05, respectively). Similarly, increases in sputum ECP (P < 0.01, P < 0.001, and P = 0.07, respectively) and sputum cys-LT levels (P = 0.07, P < 0.001, and P < 0.05, respectively) were detected in children belonging to these three groups at T(24). Sputum eosinophils significantly correlated with blood eosinophils (r = 0.54, P < 0.001) and sputum ECP (r = 0.58, P < 0.001) at T(24). This study showed that nasal allergen challenge increased markers of eosinophilic inflammation in both upper and lower airways of children monosensitized to mites, even before the onset of clinical symptoms.

Sublingual immunotherapy in mite-sensitized children with atopic dermatitis: A randomized, double-blind, placebo-controlled study

Atopic dermatitis often has an allergic component, and immunotherapy may therefore prove beneficial. To assess the effect of sublingual immunotherapy (SLIT) in children with atopic dermatitis. Children age 5 to 16 years with atopic dermatitis (Scoring Atopic Dermatitis [SCORAD] > 7) and sensitization to dust mites alone, without food allergy or chronic asthma, were enrolled in a randomized, double-blind, placebo-controlled study and stratified according to disease severity. SLIT or placebo was given for 18 months in addition to standard therapy. SCORAD, visual analog scale, and rescue medication consumption were recorded at 3-month intervals. Fifty-six children were enrolled, and 28 were allocated to SLIT. Forty-eight completed the study, with 2 dropouts in the active and 6 in the placebo group. The difference from baseline in the SCORAD was significant (P = .025) between the 2 groups starting from month 9. Similarly, there was a significant reduction in the use of medications only in the active group. A trend toward significance was seen for the visual analog score only in the active group versus baseline (P = .07). A significant difference in the considered parameters was found only in patients with a mild-moderate disease, whereas severe patients had only a marginal benefit. SLIT had to be discontinued in 2 patients because of exacerbation of dermatitis. Sublingual immunotherapy to dust mite improves mild-moderate atopic dermatitis. Sublingual immunotherapy may represent an additional therapeutic tool for the treatment of extrinsic atopic dermatitis in properly selected children.

Atopy patch testing in children with asthma and rhinitis symptoms allergic to house dust mite

The atopy patch test (APT) is generally used to assess immunoglobulin E (IgE) mediated sensitization to allergens in patients with atopic dermatitis, but its diagnostic role in children with respiratory allergy is still controversial. The aim of the study was to evaluate APT with house dust mite (HDM) in children with asthma and rhinitis symptoms allergic to HDM and its relevance to skin prick test (SPT) diameters and specific IgE levels. The study population consisted of 33 children, aged 8-16 yr (median: 12 yr) with asthma and 30 children with allergic rhinitis in the same age range (median: 11 yr). All patients had positive SPT results and high serum specific IgE levels for Dermatophagoides pteronyssinus APT was performed on back skin of all patients with 200 index of reactivity (IR)/ml of D. pteronyssinus allergen extracts in petrolatum (Stallerpatch) and evaluated at 72 h. Of 63 patients, 16 (25%) showed a positive patch test result. APT with HDM showed 30% (10/33) positivity among the patients with asthma and 20% (6/30) positivity among the patients with allergic rhinitis. APT presented no significant correlation with age, SPT diameter, serum total and specific IgE levels for D. pteronyssinus, nasal provocation test or pulmonary function test results. Patch testing with HDM may partly identify mite sensitive children with respiratory allergy. Positive APT results may imply that delayed hypersensitivity reactions play a role in children with asthma and rhinitis allergic to HDM.

The prevalence of reported asthma is independent of exposure in house dust mite-sensitized children.

In areas with low house dust mite (HDM) allergen exposure, both mite sensitization and asthma prevalence are low. In most other areas, HDM allergen exposure is higher than the threshold for sensitization. In this setting, is HDM allergen exposure a factor which is causally related to the development of asthma in HDM-sensitive individuals? To answer this question, the cumulative prevalence of asthma was evaluated in a group of 157 schoolchildren, aged 10 and 11 yrs, who were allergic to HDM allergen, and compared it with HDM allergen exposure and atopic status, using univariate and multivariate analysis. HDM allergen levels were measured in mattress dust using an enzyme-linked immunosorbent assay (ELISA) method. Of mattress dust samples, 94% had an HDM allergen level >2 microg x g dust(-1). Atopy was evaluated by means of skin prick tests using five common allergens. Among the predictive variables studied by means of univariate analysis, only the number of positive skin tests and male sex correlated with asthma prevalence, but not HDM allergen exposure. Logistic regression analysis also demonstrated that the number of positive skin tests correlated with asthma prevalence (odds ratio (OR)=1.38, p=0.05), whereas the OR for HDM allergen exposure was 1.0. This survey suggests that, in a geographical area with high HDM allergen exposure, asthma prevalence is not linked with HDM allergen levels.

The Melbourne House Dust Mite Study: Eliminating house dust mites in the domestic environment

Background: Hypersensitivity to house dust mite allergens is associated with increased asthma morbidity. Asthma severity appears to be related to the degree of mite allergen exposure. Short-term studies suggest that complete avoidance reduces disease severity. Objective: The study was designed to assess the effect of different mattress covers and floor coverings on mite allergen concentrations in the homes of mite-sensitive children with asthma in the city of Melbourne, Australia. Methods: Mite allergen Der p 1 concentration was measured on mattress covers, mattress surfaces, and carpeted and uncarpeted floors in 107 dwellings; and measurement was performed on three occasions over a 5-month period. After the first sampling, all mattress covers and impermeable encasements were permanently removed. Results: The initial geometric mean concentrations of Der p 1 (micrograms per gram of fine dust) from the surfaces of sheepskin, wool, and cotton mattress coverings were greater than those from the surfaces of impermeable mattress encasements (116, 113, and 19 vs 0.4) ( p < 0.001); corresponding concentrations on the underlying mattresses were 142, 38, 20, and 0.6, respectively ( p < 0.05 to 0.001). At the end of the study these mattress surface concentrations were 79, 65, 9.7, and 3.1, respectively. In 24 dwellings an uncarpeted room was adjacent to a carpeted room. At each visit the concentration of Der p 1 in uncarpeted rooms was below the reported threshold for sensitization and significantly less than that in the adjacent carpeted room. Conclusion: In homes of children with asthma, “asthmogenic” concentrations of Der p 1 were found on nonencased mattresses and carpeted floors, but the use of impermeable mattress encasements and carpet exclusion were associated with concentrations of Der p 1 below the reported threshold for sensitization. (J Allergy Clin Immunol 1997;99:323-9.)

ANTIGEN AVOIDANCE IN A MOUNTAIN ENVIRONMENT: INFLUENCE ON BASOPHIL RELEASABILITY IN CHILDREN WITH ALLERGIC ASTHMA

Prolonged stays in a mite-free environment by mite-sensitive children with asthma produce a significant improvement in bronchial hyperreactivity and in antigen-induced histamine release from basophils.

Immune reactivity to Der p I and Der p II in house dust mite sensitive patients attending paediatric and adult allergy clinics.

A comparison was made of immune responses to house dust mite allergens in symptomatic patients from paediatric and adult allergy clinics. IgE-specific immune reactivity to Dermatophagoides pteronyssinus was examined by Western blotting and, for Der p I and Der p II, by radioimmune dot-blot using purified allergens. Nineteen mite-sensitive children (mean age 9 years) and 26 adults (mean age 31 years) were compared. Positive IgE responses by dot-blot were found to Der p I and Der p II in 79% of children, whereas reactivity was only present in 23% and 19% respectively of adults, and densitometry indicated a weaker response. In children, Western blotting indicated that the majority of the serologic reactivity was directed to Der p II (17/19, 89%) or a 100 kDa fraction whereas in adults, reactivities were generally directed to other fractions with only 15/26 (58%) recognizing Der p II. Consistent with results of others, a fraction corresponding to Der p I was poorly detected on Western analysis despite positive dot-blots. To determine whether the relative lack of IgE serological immune reactivity in adults was associated with a similar lack of cellular recognition, T-cell proliferation studies were performed, also using purified allergens. Interestingly, these revealed that cellular responsiveness, without serological reactivity, was present in 29% of subjects to Der p I and 50% to Der p II. Proliferative responses were evident in all individuals with specific IgE.

Measurement of IgE specific to a major allergen of house dust mite: Der p I

A monoclonal antibody assay has been developed to measure Der p I specific IgE in sera of D. pteronyssinus sensitive patients. In this assay a specific monoclonal antibody was bound to the solid-phase and this complex was used for insolubilization of the allergen. Two procedures using two different solid-phases, CNBr activated paper discs and microtitre plate wells, were compared. In the paper disc assay about 90% of specific IgE was bound to the solid-phase. A study of 80 sera from mite sensitive children confirmed the importance of Der p I; indeed all the sera contained Der p I specific IgE and IgE anti Der p I contributed from 5% to 100% (mean = 39%) of the mite specific IgE response. In the microtitre plate assay only 45% of specific IgE was immobilized and it was necessary to express the results in arbitrary units. The correlation with the paper disc assay was significantly positive ( r = 0.89) but five samples were found to be negative. However, this assay appears to be of interest for studying the affinity of specific IgE in different samples. The use of specific monoclonal antibodies as allergosorbents is a useful approach to a better standardization of the in vitro diagnostic reagents.