Seasonal differences in airway hyperresponsiveness in asthmatic patients: relationship with allergen exposure and sensitization to house dust mites

Background The degree of airway hyperresponsiveness in allergic asthmatic patients may be influenced by changes in environmental exposure to inhalant allergens. Objective This study investigates the relationship between seasonal changes in exposure to house dust mite (HDM) allergens and non-specific airway hyperresponsiveness in asthmatic patients with multiple sensitizations to inhaled allergens. Methods In 43 asthmatic patients sensitized to several inhalant allergens, lung function (FEV₁), airway hyperresponsiveness (PC₂₀ histamine), serum total IgE, house dust mite (HDM) specific IgE and number of peripheral blood eosinophils were measured during autumn 1990 (September-November) and spring 1991 (March—May). During each season. floor dust samples were collected twice from living- and bedrooms and the concentration of the HDM allergens Der p 1 and Der p 2 determined. Results More severe airway hyperresponsiveness (lower PC₂₀ histamine) during autumn was only found in patients sensitized to HDM(n= 32; autumn: 2.05mg/mL, spring: 4.51mg/mL (geometric means), P <0.0 1), whereas in patients not sensitized to HDM (n= 11) similar values were observed in both seasons (3.44 and 4.52 mg/mL. respectively, P= 0.56). More severe airway hyperresponsiveness of HDM sensitized patients in autumn was significantly associated with higher Der p 1 concentrations in floor dust. Aside from airway hyperresponsiveness, seasonal changes in serum total IgE and number of peripheral blood eosinophils were seen in patients sensitized to HDM, Conclusions In allergic asthmatic patients, airway hyperresponsiveness may increase during autumn, depending on sensitization to HDM and an increase of exposure to HDM allergen.     

Allergenic crossreactivity between Lepidoglyphus destructor and Blomia tropicalis

Background In general, the non-pyroglyphid mites Lepidoglyphus destructor and Blomia tropicalis show a different geographical distribution. Allergic sensitization to both species have been demonstrated in several investigations. However, whether this reflects crossreactivity or dual sensitization is so far not known. Objective The aim of the study was to investigate the allergenicity and allergenic crossreactivity of L destructor and B. tropicalis using sera from Sweden and Brazil. Objective Allergens in extracts of L. destructor and B. tropicalis were identified with SDS-PAGE and immunoblotting and the crossreactivity was studied by an immunoblot inhibition method. In addition to mite extracts, a recombinant major allergen of L destructor, Lep d 2, was used. Results The extract prepared from L. destructor contained 21 IgE-binding components when using the Swedish or the Brazilian sera. A 15 kDa allergen was recognized by 85% of the Swedish sera and 78% of the Brazilian. The B. tropicalis extract exposed 23 IgE-binding components when the Brazilian sera were used and 19 when the Swedish sera were used. A total of 83% of the Brazilian sera and 80% of the Swedish sera identified a 14.5 kDa allergen. The IgE response of the Swedish serum pool to 10 B. tropicalis allergens was inhibited by L. destructor extract. Likewise, the response of the Brazilian serum pool to four different L. destructor allergens was inhibited by B. tropicalis extract. The recombinant Lep d 2 allergen inhibited 33% of the IgE binding of the Swedish serum pool to the 14.5 kDa allergen in the B. tropicalis extract. Conclusion crossreactivity with several proteins from L. destructor and B. tropicalis was demonstrated. The results suggest that a B. tropicalis 14.5 kDa allergen is antigenically crossreactive with recombinant L. destructor allergen Lep d 2.     

Prevalence and distribution of indoor allergens in Singapore

Background and aims Immediate hypersensitivity to indoor allergens is known to be associated with allergic asthma. This study evaluated the prevalence and distribution of six indoor allergens in 956 dust samples obtained from homes, childcare centres, schools, and a hospital in tropical Singapore. Seasonality of mite allergens was also assessed. Methods The major allergens of the Dermatophagoides spp. dust mites, Der p l and Der f 1; major cat and dog allergens, Can f 1 (dog) and Fel d 1 (cat); and cockroach, Bla g 1. were measured by specific enzyme immunoassays. Allergen levels of the storage mite. Blomia tropicalis (Blot), were measured by a fluorescent allergosorbent test (FAST) inhibition assay. Results Our results showed that homes had significantly higher concentrations and prevalence of allergens compared with the other locations, except for Bla g 1, where higher mean levels were found in schools. Within the homes, the highest concentrations of mite allergens were found in mattresses (geometric mean: 1.2 μg/g dust Der p 1; 2717 Allergen Units per gram dust [AU/g] Blot), and carpets (1.5 μg/g Der p 1; 1620 AU/g Blo t), whilst Bla g 1 was mainly concentrated in the storerooms (geometric mean = 3.5 units/g) and kitchens (geometric mean = 5.1 units/g). The major cat and dog allergens were well distributed and not confined to homes with pets. Their highest levels were found in dust of soft furnishings, carpets and mattresses. There was an absence of significant seasonal variation in Der p 1, Der f 1 and Blo t levels in the homes over a 1 year period. Conclusion The results indicate that compared with public places, the home consitutes a major reservior of indoor allergens. Allergens of the storage mite, B. tropicalis, should be considered as a major allergenic component of dust in Singapore.     

Mite fauna of German farms

Storage mites are important sources of airborne allergens, especially on farms. A mite survey was conducted in the working environments of 121 farms in five regions of Germany. Of 859 samples, 743 (86.4%) contained mites, representing 547 857 astigmatic mites in 723 g of dust and 34 501 prostigmatic mites in 469 g of dust. Dust samples from nine sites of each farm were collected and analyzed. Ninety-three percent of all mites belonged to the order Astigmata (storage- and house-dust-mite species); 35 Astigmata and 14 Prostigmata mite species were identified. According to the abundance and steadiness of the important astigmatic mite species, the following order was found: Lepidoglyphus destructor > Glycyphagus domesticus > Acarus siro > Tyrophagus longior > Blomia tjibodas > Chortoglyphus arcuatus > Thyreophagus entomophagus > Tyrophagus putrescentiae > Euroglyphus longior > Tyrophagus palmarum > Acarus farris > Acarus immobilis > Gohieria fusca. Blomia tjibodas was described for the first time as an abundant species of farms in Germany.     

Severity of atopic dermatitis in relation to food and inhalant allergy in adults and adolescents

The aim of this study is the evaluation of the relationship between the severity of atopic dermatitis (AD) and the occurrence of IgE-mediated food allergy, food sensitization, and sensitization to inhalant allergens. The complete dermatological and allergological examinations were performed and the severity of AD was evaluated with the SCORing Atopic Dermatitis index. The statistical evaluation of the relationship between the occurrence of IgE-mediated food allergy, food sensitization, sensitization to inhalant allergens, and the severity of AD was performed. Two hundred and eighty-three patients were examined, 89 men and 194 women, average age 26.2 (s.d. 9.5). The significant relation was recorded between the severity of AD and sensitization to tested inhalant allergens. The significant relation was also found between the severity of AD and IgE-mediated food allergy. It turns out that the higher time to reaction, the higher the severity of AD.     

新疆医学院校部分大学生面部蠕形螨感染调查分析

目的了解新疆医学院校部分学生人体蠕形螨的感染现状,为治疗和预防提供依据。方法采用透明胶带粘贴法,对部分在校集体住宿的大学生进行蠕形螨面部感染的调查。结果共调查640名学生,总感染率为10．94％（70／640）,两侧鼻翼较额头蠕形螨检出率高。男生感染率为8．21％（17／207）,女生感染率为12．24％（53／433）,二者感染率差异无统计学意义（X^2=2．33,P〉0．05）;汉族学生感染率为7．22％（20／277）,少数民族学生感染率为13．77％（50／363）,二者感染率差异有统计学意义（X^2=6．93,P〈0．01）;非集体聚集人群（一年级新生）感染率为18．18％（8／44）,集体聚集人群（二、三年级学生）感染率为10．40％（62／596）,二者感染率差异无统计学意义（X^2=1．81,P〉0．05）。结论新疆医学院校部分学生蠕形螨总感染率较低,感染者有明显的民族差异现象。