Analysis of basophil activation by flow cytometry in pediatric house dust mite allergy

Detection of allergen‐induced basophil activation by flow cytometry has been shown to be a useful tool for allergy diagnosis. The aim of this study was to assess the potential of this technique for the diagnosis of pediatric house dust mite allergy. Quantification of total and specific IgE and basophil activation test were performed to evaluate mite allergic (n = 24), atopic (n = 23), and non‐allergic children (n = 9). Allergen‐induced basophil activation was detected as a CD63‐upregulation. Receiver operating characteristics (ROC) curve analysis was performed to calculate the optimal cut‐off value of activated basophils discriminating mite allergic and non‐allergic children. ROC curve analysis yielded a threshold value of 18% activated basophils when mite‐sensitized and atopic children were studied [area under the curve (AUC) = 0.99, 95% confidence interval (CI) = 0.97–1.01, p < 0.001] with a sensitivity and specificity of 96% for 16 μg/ml mite extract. Analysis of the data obtained with 1.6 μg/ml mite extract defined a cut‐off value of 8% activated basophils (AUC = 0.96, 95% CI = 0.91–1.01; p < 0.001) with a sensitivity of 82% and specificity of 100%. Comparison between mite allergic and non‐allergic children produced a cut‐off of 8% activated basophils (AUC = 1.0) with 16 μg/ml allergen extract and a sensitivity and specificity of 100%. The same threshold and specificity values were obtained with 1.6 μg/ml extract (AUC = 97%, 95% CI = 0.92–1.02; p < 0.001) but sensitivity decreased to 83%. Two atopic children showed negative skin prick and basophil activation tests and high specific IgE (>43 kU/l) values for Dermatophagoides pteronyssinus allergen. They also showed positive prick (wheal diameter >1.0 cm) and basophil activation (>87%) tests and high specific IgE (>100 kU/l) with shrimp allergen. Shrimp sensitization was demonstrated by high levels of Pen a 1‐specific IgE (>100 kU/l). Cross‐reactivity between mite and shrimp was confirmed by fluorescence enzyme immunoassay (FEIA‐CAP) inhibition study in these two cases. This study demonstrated that the analysis of allergen‐induced CD63 upregulation by flow cytometry is a reliable tool for diagnosis of mite allergy in pediatric patients, with sensitivity similar to routine diagnostic tests and a higher specificity. Furthermore, this method can provide additional information in case of disagreement between in vivo and in vitro test results.     

Localization of a major allergen, Der p 2, in the gut and faecal pellets of Dermatophagoides pteronyssinus

BACKGROUND: The house dust mite Dermatophagoides ptronyssinus is one of the most significant indoor sensitizing agents of allergy. Allergen localization may indicate the importance of secreted materials, faeces, and nonexcreted mite body components as allergen sources. OBJECTIVE: This study attempted to localize the sites and concentrations of Der p 2 in the cryostat sections of D. pteronyssinus using antirecombinant Der p 2 monoclonal antibody. METHODS: Male and female mites and mite faeces collected separately from both sexes were used. Live mites were embedded and serial cryostat sections for light microscopy were performed. Anti-recombinant Der p 2 monoclonal antibody previously produced by the authors was used. For immunoprobing, mite cryostat sections were incubated in the following antibody-containing solutions: monoclonal antibody against Der p 2 was initially applied to the sections and fluorescent isothiocyanate conjugated antimouse immunoglobulin G was reacted as the secondary antibody. The faecal pellets were treated the same as described above. RESULTS: Immunofluorescent probing of cryostat sections with the monoclonal antibody showed labelling of the gut lining, gut contents and defecated faecal pellets. No other internal organs were identified as positively labelled. CONCLUSION: This study suggested that a major allergen, Der p 2, found in the house dust mite D. pteronyssinus is derived from the digestive tract and concentrated in the faeces.     

Molecular cloning and characterization of full-length cDNAs encoding a novel high-molecular-weight Dermatophagoides pteronyssinus mite allergen, Der p 11

BACKGROUND: Dermatophagoides pteronyssinus (Dp) and D. farinae (Df) mites are the most important source of indoor aeroallergens. Most Dp mite allergens identified to date have relatively low molecular weights (MWs). Identification of high-MW mite allergens is a crucial step in characterizing the complete spectrum of mite allergens and to provide appropriate tools for diagnostic and therapeutic application. METHODS: The full-length Der p 11 cDNA clone was isolated using cDNA library immunoscreening, the 5'-3' rapid amplification of cDNA ends (RACE) system and polymerase chain reactions (PCR). The whole cDNA insert and its PCR-derived DNA fragments (p1 to p4) were generated and expressed in the Escherichia coli expression system. The allergenicity of the recombinant protein and its peptide fragments was examined by IgE immunodot assays. The IgE-binding reactivity of rDer p 11 was analyzed in the serum of 50 asthmatic children with positive reactivity to Dp mite extract. Its recombinant peptide fragments were also examined by immunodot assays in 30 mite-allergic children. RESULTS: Der p 11 cDNA consists of a 2625-bp open reading frame encoding a 103-kDa protein with 875 amino acids. It exhibits significant homology with the paramyosin of other invertebrates. The protein sequence alignment of this newly identified Dp mite allergen (denominated as Der p 11) revealed over 89% identity with Der f 11 and Blo t 1. Among 50 Dp-sensitive asthmatic children, rDer p 11 showed positive IgE-binding reactivity to 39 patients (78%). Using immunodot assays, multiple human IgE-binding activities were demonstrated in all four fragments of Der p 11. Using immunoblot assays, the dominant IgG-binding epitope for monoclonal antibody (mAb642) was located in fragment p3 only. In immunoblot assays, cross-inhibition between rDer p 11 and rDer f 11 was up to 73-80% at concentrations of 100 microg/ml. CONCLUSIONS: This study confirms that the newly identified recombinant Der p 11 is a novel and important high-MW Dp mite allergen for asthmatic children. Our data also indicates that human IgE-binding major epitopes are scattered over the entire molecule of Der p 11.     

Airway generation-specific differences in the spatial distribution of immune cells and cytokines in allergen-challenged rhesus monkeys

BACKGROUND: Accumulation of immune cell populations and their cytokine products within tracheobronchial airways contributes to the pathogenesis of allergic asthma. It has been postulated that peripheral regions of the lung play a more significant role than proximal airways with regard to inflammatory events and airflow obstruction. OBJECTIVE: To determine whether immune cell populations and associated cytokines are uniformly distributed throughout the conducting airway tree in a non-human primate model of allergic asthma. METHODS: We used a stereologic approach with a stratified sampling scheme to measure the volume density of immune cells within the epithelium and interstitium of trachea and 4-5 intrapulmonary airway generations from house dust mite (HDM) (Dermatophagoides farinae)-challenged adult monkeys. In conjunction with immune cell distribution profiles, mRNA levels for 21 cytokines/chemokines and three chemokine receptors were evaluated at four different airway generations from microdissected lungs. RESULTS: In HDM-challenged monkeys, the volume of CD1a+ dendritic cells, CD4+ T helper lymphocytes, CD25+ cells, IgE+ cells, eosinophils, and proliferating cells were significantly increased within airways. All five immune cell types accumulated within airways in unique patterns of distribution, suggesting compartmentalized responses with regard to trafficking. Although cytokine mRNA levels were elevated throughout the conducting airway tree of HDM-challenged animals, the distal airways (terminal and respiratory bronchioles) exhibited the most pronounced up-regulation. CONCLUSION: These findings demonstrate that key effector immune cell populations and cytokines associated with asthma differentially accumulate within distinct regions and compartments of tracheobronchial airways from allergen-challenged primates.     

Suppression of allergen-specific B lymphocytes by chimeric protein-engineered antibodies

House dust mites Dermatophagoides pteronyssinus (Dpt) are among the most frequent causes of allergy symptoms in Europe. Der p 1 is one of the major allergenic compounds of Dpt and the pathological Der p 1-specific B cells play a key role as producers of allergen-binding antibodies. The selective elimination of these cells by artificial protein molecules which inhibit the production of Dpt-recognizing IgE antibodies is a perspective therapeutic goal of allergy.     

Indoor Allergen Levels and Household Distributions in Nine Cities Across China

Objective Chinese allergic subjects have high levels of sensitization to house dust mite (HDM) and other indoor allergens. This study quantifies common indoor allergen levels in Chinese households.
Methods Dust samples were collected from nine cities. Major allergens Der p 1 and Der f 1 from Dermatophagoides pteronyssinus and D. farinae, and specific antigens of Blomia tropicalis, Tyrophagus putrescentiae, Acarus siro, and cockroach species Blattella germanica and Periplaneta americana were measured by ELISA.
Results HDM allergens were found in dust samples from bedding in 95% of the Chinese households. The median levels varied from <0.006 to 9.2 μg/g of dust, depending on the city. The percentages of households having HDM allergen levels associated with the risk of developing allergy sensitization and asthma were 65% and 25%, respectively. Specific antigens of the storage mite and cockroach were only found in samples from the southern and tropical regions of China. Levels of mite allergens were generally higher in samples from bedding compared to samples from the living room, even for storage mites, whereas levels of cockroach antigens were higher in the living room samples.
Conclusion HDM allergens are present in bedding dust samples from most Chinese households. Cities in southern and central China have relatively high levels of HDM major allergens compared to cities in northern and western China. Antigens of storage mites and cockroaches are not as common as HDM allergens.     

粉尘螨(浸液)抗原PLGA微球的制备及其性质的研究

目的 制备粉尘螨微球并对其性质进行研究。方法 制得粉尘螨抗原浸液,以聚乳酸-乙醇酸(PLGA75/25)为包裹材料,用双乳化溶剂蒸发法制备粉尘螨微球,光镜下测定直径、分布及跨距。用抽提法检测粉尘螨微球体外缓释速率,通过灌服过荧光微球(在粉尘螨抗原浸液中加入罗丹明B)不同时间的小鼠派氏集合淋巴结(Pey-er’s potches,PP)组织切片来测定其在小鼠体内的缓释作用。结果 粉尘螨微球的直径为(7.6±1.4)μm,跨距为0.54,符合正态分布,载药量为7.4％。体外释药呈双相特征,0～2天呈快速释放,4～32天为慢速释放相。小鼠灌服微球后,第1、15天都能在小鼠PP内找到微球。结论 此方法制备的粉尘螨微球达到缓释制剂的要求,可以用于对致敏小鼠的脱敏研究。     

屋尘螨cDNA表达文库的构建及初步鉴定

目的构建屋尘螨cDNA表达文库. 方法用RNAiso Reagent试剂盒提取屋尘螨Total RNA,用Poly AT tract mRNA分离试剂盒提取mRNA,用Clontech公司SMARTTM PCR cDNA library kit反转录合成第1链cDNA,用LD-PCR合成第2链cDNA并扩增,PCR产物与MaxPlax TM试剂盒体外连接包装,建成未扩增的cDNA文库,计算其滴度和重组效率后进行文库扩增并测定扩增文库的滴度. 结果cDNA文库未扩增时滴度为9.148×106,重组效率达93.88%以上,文库扩增后滴度为7.628×109,插入片段平均1.63 kb. 结论成功地构建了高质量的屋尘螨cDNA表达文库.