Allergen content in dust from homes and schools in northern Norway in relation to sensitization and allergy symptoms in schoolchildren

Background Previous studies have shown a high prevalence of atopic diseases among school children in the community of Sør-Varanger. Moreover, animal dander followed by pollen und house dust mite, were the most common allergens in skin prick tests. Objective To assess the allergen content in homes (living-rooms and mattresses) and classrooms of children living in an arctic area at 70° north. The presence of allergens in homes and schools and their relationship to atopy was of particular interest. Methods Dust samples from 38 homes and seven schools in northern Norway were collected by vacuum cleaning. The presence of allergens of dog, birch, timothy, Cladosporium herbanun, codfish and hen egg-white was investigated by radio-allergosorbent test (RAST) inhibition and the presence of major allergens of cat Felis domesticus (Fel d I) and house dust mites (HDM) Dermatophagoides pteronyssinus (Derp I) and Dermatophagoides farinae (Derf I) by enzyme-linked immunosorbent assay (ELISA). Results Mattresses contained significantly more dust per unit area than living-rooms and classrooms. No statistically significant differences in allergen content for dog. birch, timothy, Cladosporium, codfish and hen egg-white were seen between HDM-sensitized and non-atopic children. Most dust samples contained dog allergens with the highest allergenic activity found in living-rooms of those keeping dogs. An increased level of Feld I was detected in only one of 38 samples from living-rooms (this family kept a cat) and in 25 of 38 samples from mattresses with ranges from 24 to 84ng/m². The highest concentrations were found in mattresses of children keeping cats. Increased levels ( 25 ng/m²) of Derp I were found only in homes and virtually only in mattresses of HDM-sensitized children. An increased level of Derf] was found in only one case, i.e. in the mattress of an HDM-sensitized child where additionally Der p I and HDMs were demonstrated microscopically. When relating Der p I to HDMsensitization an odds ratio of more than 16 (95% Cl: 1.6–394.3) was found. All extracts from living-rooms included codfish allergens. Low RAST inhibition values were detected for hen egg-white, Cladosporium, birch and timothy pollen in most samples. Furthermore, the study demonstrated that dust from schools was relatively free of allergens. Conclusion Previous findings indicating that the main allergen exposure problem in this geographical area is that of pet allergens were confirmed.     

Heterogeneous proteolytic specificity and activity of the house dust mite proteinase allergen Der p I

Background Exposure of the skin or respiratory tract to proteinases is frequently associated with allergic sensitization. This is of particular significance in the domestic indoor environment where the proteolytic activity of Der p I, the group I allergen of the house dust mite Dermatophagoides pteronyssinus, may influence the allergenicity of mites. Using class-specific proteinase inhibitors and active-site affinity chromatography, we have previously shown that Der p I exhibits a mixed cysteine-serine proteinase activity. Measurement of the amount of cleavage, however, did not determine whether the inhibitors used were targeting exactly the same proteolytic mechanism. Objective To resolve this issue, we have examined whether the cleavage specificity of the cysteine and serine proteinase activities of Der p I was the same. Methods HPLC and mass spectrometry were used to analyse and identify the products of a Der p I-digested peptide substrate and thus identify the peptide bonds cleaved. Results Der p I cleaves different peptide bonds, depending upon the class of proteolytic mechanism used. In the model peptide substrate insulin B chain, the cysteine and serine proteinase activities of Der p I showed preference for glutamic acid and arginine respectively in the P1 position. Conclusion These data suggest the existence of more than one mechanistic form of the allergen immunologically identified as Der p I. If proteolytic activity is indeed a function of allergenicity, this information may have important implications for the pathogenicity of Der p I and the ability of innate antiproteinase defences in the respiratory tract to prevent immune sensitization.     

The decay of house dust mite allergens, Der p I and Der p II, under natural conditions

Background: Fluctuations in the level of mite allergens in domestic house dust are the result of changes in the balance between synthesis, removal and decay. Purely physical forces as well as enzymatic degradation, mediated by house dust inhabiting microbes, may contribute to the decay of allergens in domestic dust. Knowledge about the speed of decay is essential for an understanding of the dynamics of allergen levels. Objective: The present study is a quantitative assessment of the speed of decay at nine combinations of temperature (15°C, 20°C and 25°C) and relative humidity (33%, 55% and 75%). Methods: Samples of mite infested material of an old rug were stored at these temperature/relative humidity-combinations for 6, 12 or 18 months, after the mites were killed by cither a freezing treatment or an acaricide (lindane). The microbes living in the rug presumably survive these treatments. Concentrations of Der p I and Der p II + Der f II. in extracts of the rug material, were measured by a radio immunoassay. Results: No significant changes in the levels of Der p I and Der p II +Der f II, could be detected even after 1¹/₂ year at a high temperature and humidity. Conclusion: These findings incidate that mite allergens can be extremely stable under normal domestic circumstances.     

Human T cell responses to recombinant mite antigens of Dermatophagoides farinae

We studied T cell responses to four glutathione S transferase (GST)-fused mite antigens prepared in our laboratory using peripheral blood lymphocytes from mite-sensitive patients with bronchial asthma. Of the four recombinant antigens, purified GST-Mag3 had the strongest ability to cause patients' lymphocytes to proliferate, and its potency was almost comparable to that of crude mite bodies (Dfb) and faeces (Dff) antigens and a purified major antigen, Der f 2. The responder lymphocytes were mainly T cells, because the proliferative response was depleted by the treatment of lymphocytes with anti-CD3 antibody and complement, but not with anti-CD20 antibody and complement. The responsiveness of lymphocytes to GST-Mag3 correlated with that to Der f 2, but GST-Mag3 displayed slightly higher activity to stimulate lymphocytes than Der f 2. Simultaneously, the levels of Dff- and GST-Mag3-specific IgE antibodies correlated with the responsiveness of lymphocytes to GST-Mag3. These results suggest that Mag3 is a new valuable antigen for the response of T cell proliferation in mite-sensitive patients.     

Feather mites are potentially an important source of allergens for pigeon and budgerigar keepers

Background Previous studies on allergy to feathers have not adddressed whether orgatiisms living on feathers (mites. lice, moulds) are a source of allergens. Objective To investigate whether feather mites produced allergens of clinical relevance to bird keepers. Methods We examined serum IgE responses of 96 pigeon breeders to an extract of feather mites from pigeons (predominantly Diplaegidia columbae). using Western blotting, specific IgE assay using AlaSTAT EIA and RAST inhibition. Results Feather mites are a major source of soluble proteins derived from feathers, accounting for up to 10% of the total weight of the feather. Forty-three sera had a negative score (0) for anti-feather mite IgE. 27 were weakly positive (1–2) and 26 had strongly positive scores (3–4). Fewer pigeon breeders with scores ± 3 were asymptomatic than those with negative scores (12 versus 40%). more had late onset symptoms (with or without early onset symptoms; 77% versus 44%) and had IgE antibody against house dust mite (89% versus 23%). Western blotting of eight sera against the extract of Diplaegidia columbae revealed 20 IgE-binding components ranging from 22 to 200 kDa. A high diversity of components was recognized by each serum: arithmetic mean 7 (range 2 14). RAST inhibition indicated feather mites had species-specific epitopes as well as ones that cross-reacted with Dermatophagoides pteronyssinus. Conclusion Strongly-positive AlaSTAT scores to pigeon leather mite were associated with allergic symptoms of late onset in pigeon breeders. We conclude that feather mites are a major source of clinically-relevant allergens for pigeon breeders.     

Distinctive immunoglobulin E anti-house dust allergen-binding specificities in a tropical Australian Aboriginal community

BACKGROUND: There is evidence that the specificity of the IgE binding in allergy tests can vary for different populations. OBJECTIVE: We aimed to examine the allergenic specificity of IgE binding in sera from house dust mite (HDM)-atopic subjects in a tropical Australian Aboriginal community. METHODS: Sera shown to contain IgE antibodies to an HDM extract of Dermatophagoides pteronyssinus were examined for IgE binding to a panel of nine purified HDM allergens from this mite species by quantitative microtitre assays. IgG antibody binding (IgG1 and IgG4) was also measured. RESULTS: The IgE-binding activity in the sera from the Aboriginal community was not directed to the expected major groups 1 and 2 HDM allergens but instead to the group 4 amylase allergen. There was also little IgE binding to the potentially cross-reactive tropomyosin (Der p 10) or arginine kinase (Der p 20) allergens. The IgG4 antibody was rarely detected and limited to the Der p 4 allergen. IgG1 antibody binding was frequently measured to all the allergens regardless of an individual's atopic status, whereas in urban communities it is restricted to the major allergens and to atopic subjects. CONCLUSION: The high IgE anti-HDM response of Australian Aboriginals predominantly bound Der p 4 and not the Der p 1 and 2 allergens, showing a distinctive allergy that could affect the disease outcome and diagnosis.     

粉尘螨主要变应原Derf1基因的改造与可溶性表达

目的在大肠杆菌中提高粉尘螨1类变应原（Derf1）的可溶性表达。方法用RT-PCR方法扩增得到Derf1的全长序列与成熟肽序列（mDerf1）；以已知DerP5基因的前导序列替换Derf1前导序列和原酶序列，重新构建出rDerf1基因；将上述3个基因分别克隆入原核表达载体pGEX-4T-1中表达，经Western-blot对三者的表达产物进行分析鉴定。结果Western-blot表明，pGEX-Derf1与pGEX-mDerf1的表达产物分别为分子量约63000与51000的重组蛋白质，重组蛋白质主要存在于细胞裂解液的沉淀中。pGEX-rDerf1大量表达了可溶性目的蛋白质，分子量约53000，并被成功地分离纯化。以上三种表达产物均可被鼠抗GST抗体与螨过敏患者血清特异地识别。结论表达了含Derf1，mDerf1与rDerf1的三种GST融合蛋白质，它们均具免疫反应性，纯化获得了GST-rDerf1融合蛋白质，为后期的诊断及治疗奠定了基础。     

Fenoterol, a selective beta2-adrenergic agonist, and inhibition of IgE-mediated basophil histamine release

The present study was undertaken to evaluate the effect of fenoterol, a selective beta 2-adrenergic agonist, on basophil histamine release. Fenoterol at 10(-7) to 10(-3) M did not inhibit the release of histamine induced by Dermatophagoides farinae extract (D.f.) from leukocytes from allergic patients sensitive to mite. Similarly, there was no suppression of histamine release induced by anti-IgE and formyl-methionyl-leucyl-phenylalanine under the influence of fenoterol. Fenoterol caused a slight inhibition of the calcium ionophore A23187-induced histamine release at 10(-3) M with % inhibition of 11.8 +/- 2.4 (means +/- SEM, P less than 0.05). There was no synergism between fenoterol and theophylline in inhibiting D.f.-induced histamine release. Fenoterol did not suppress the release of histamine induced by antigen at low as well as high levels of release. Based on the data on the effect of fenoterol on IgE-mediated histamine release, it was concluded that in contrast to a human lung mast cell system, the beta-adrenergic receptor-adenylate cyclase system is not a control mechanism in IgE-mediated basophil histamine release.     

Monoclonal anti-human IgG antibodies for quantitation of allergen-specific IgG in human sera

Eight monoclonal anti-human IgG antibodies were fully characterized and evaluated as possible reagents in solid phase radioimmunoassay for quantitating allergen-specific IgG antibody. Four monoclonal antibodies (HG24D, HG2-14, HG2-18, and HG2-25) recognize CH2 domain of human IgG and bind to human IgG fixed to microtiter plate with high affinities. These monoclonal antibodies were more suitable than polyclonal rabbit anti-human IgG antibody in Phadebas RAST for honey bee venom-specific IgG antibody. Nonspecific binding was much lower, and the slopes of standard curves were much steeper. In contrast to polyclonal antibody, the standard curve was hardly influenced by human serum IgG in sample diluent. These advantages of monoclonal antibodies that recognize CH2 domain of human IgG made it possible to quantitate egg white- and Dermatophagoides pteronyssinus-specific IgG antibodies with use of allergen disks prepared for IgE RAST. This property allows a single system to be used for measurement of IgG and IgE antibodies against clinically relevant allergens.     

Sensitization to Dermatophagoides siboney, Blomia tropicalis, and other domestic mites in asthmatic patients

Mite species adapted to warm, humid climates are commonly found in house dust in the tropics. In Cuba, Dermatophagoides pteronyssinus, D. siboney , and Blomia tropicalis are the most common and abundant mite species in house dust. To investigate the pattern of Sensitization of Cuban asthmatic patients to common mite species, we skin-prick-tested (SPT) 148 patients with a clinical history of asthma and possible mite allergy, and determined specific IgE antibodies against mite allergens ( D. pteronyssinus, D. farinae, D. siboney, B. tropicalis, Acarus siro, Lepidoglyphus destructor, Tyrophagus putrescentiae , and Glycyphagus domesticus ). The prevalence of positive SPT was high to D. siboney (88%), D. pteronyssinus (87%), A. siro (85%), B. tropicalis (85%), and D. farinae (83%). The largest skin reactions were obtained with D. siboney and B. tropicalis extracts. The skin test response to the D. siboney extract correlated to those of D. farinae, D. pteronyssinus, B. tropicalis , and A. siro. The highest IgE levels were found to Dermatophagoides species and B. tropicalis. IgE to D. siboney and B. tropicalis were found in 97% and 96% of the patients, respectively. The prevalence of specific IgE to the other mites studied varied from 46 to 65%. D. siboney and B. tropicalis are important sensitizers among asthmatic patients in Cuba.