The fall of the Berlin wall in 1989 offered the unique opportunity to compare populations of a similar genetic and geographic background which had been living under quite different environmental exposure conditions for over 40 years. Since 1990 comparative epidemiological studies were performed between various regions in former East and West Germany with yearly questionnaires and 3 years' physical, dermatological, allergological and exposure examination in a total of about 30,000 preschool children. There were striking differences between the various German regions with higher prevalence rates of respiratory atopy (hay fever, asthma) and atopic sensitization (prick test, RAST) in West Germany, while atopic eczema was significantly higher in East Germany (17.5 vs. 11.4% in West Germany). Total serum IgE levels were markedly higher in children in the east of Germany, similarly to the prevalence of parasitic infestation (questionnaire data as well as positive ascaris RAST). In multivariate logistic regression analysis the following factors were significantly associated with atopic eczema: animal contact (odds ratio, OR 2.9), animal furs in the bedroom (OR 2.2), use of gas without ventilation (OR 1.7) and living near road with heavy traffic (OR 1.7). Furthermore, socioeconomic factors measured as parental educational status (university vs. elementary school) were significantly associated (OR 2.3) with atopy. Respiratory tract infections and irritant responses decreased together with decreasing SO2 and suspended particulate air pollution in East Germany from 1991 to 1997. It is concluded that environmental factors from the physical, chemical, biological, and psychological environment (characteristic of a 'modern' or 'western' society) do influence the development of atopic sensitization and disease.

Allergens↗

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Timothy grass (Phleum pratense L.) pollen as allergen carriers and initiators of an allergic response.

Contrary to indoor allergen exposure (e.g. house dust mite), there is no reliable quantitative association between pollen exposure and symptoms of allergic diseases. Therefore we studied localization and release of major allergens from timothy grass (Phleum pratense L.) pollen using different methods and pollen grain sources. Localization of major allergens Phl p 5 and Phl p 1 was visualized by field emission scanning electron microscopy after anhydrous fixation and immunogold silver staining in a three-dimensional reconstruction; Phl p 5 was found in the cytoplasm and on the exine, Phl p 1 in the intine. No allergens were found inside the starch granules. Allergen liberation from pollen grains was studied in vitro under physiological conditions (30 min, 37 degrees C) at pH 6. 0, 7.4 and 9.0. Besides total protein measurements in the supernatant, major allergens were determined by immunoblot, Phl p 5 was quantitated by ELISA. There were striking differences in total protein and major allergen release between freshly collected and commercially available grass pollen grains as well as among freshly collected pollen between rural meadows and areas near high-traffic roads. There was a significantly different release of total protein being lowest in supernatants from commercially available pollen grains (rural/traffic vs. commercial, p<0.001), and of Phl p 5 major allergen (rural>traffic>commercial, p<0.005). Therefore, allergen bioavailability seems to be an important parameter in order to establish reliable dose-response relationships for the outdoor allergen response. Pollen grains incubated in aqueous protein-free buffer solution were also found to secrete significant amounts of eicosanoids namely prostaglandin E2 and leukotriene B4. Pollen grains thus do not act only as allergen carriers but also might have important implications on early events as initiators of allergy.

Allergens↗

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Enu mouse mutagenesis: generation of mouse mutants with aberrant plasma IgE levels.

BACKGROUND: The ENU Mouse Mutagenesis Project aims at a large-scale, systematic production of mouse mutants using the alkylating agent ethyl-nitrosourea (ENU). Offspring of mutagenized mice are subjected to a multiparameter screen to detect alterations in various phenotypes with the ultimate goal of identifying novel genes relevant for the expression of the phenotype. Using this approach, we have analyzed plasma IgE concentrations to identify mouse mutants with aberrant plasma IgE levels. METHODS AND RESULTS: ENU-mutagenized male C3HeB/FeJ were mated to wild-type females to produce F1 offspring. F1 animals were analyzed for alterations in their plasma IgE concentrations that showed a dominant mode of inheritance, or bred further to screen for recessive phenotypes. Plasma IgE concentrations were determined by ELISA and a normal range for plasma IgE was established using C3HeB/FeJ wild-type animals. So far we have tested 6568 F1 animals. Repeated testing confirmed a stable aberrant IgE phenotype in 124 animals. To confirm the genetic basis of the observed phenotype, these mice were subjected to confirmation crossing. Currently we have established 9 independent mutant mouse lines (3 with high plasma IgE and 6 with plasma IgE below detection limit) that have been genetically confirmed and additional 24 variant mouse lines are currently undergoing confirmation testing. CONCLUSION: ENU mouse mutagenesis allowed us to generate and identify mouse mutants with aberrant plasma IgE levels, which may be used to characterize novel genes involved in IgE regulation and may serve as animal models for IgE-mediated diseases.

Alkylating Agents↗

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Secretion of proinflammatory eicosanoid-like substances precedes allergen release from pollen grains in the initiation of allergic sensitization.

It is commonly believed that allergic sensitization starts when an allergen contacts the surface of an antigen-presenting cell in mucosal or skin epithelia. Most studies dealing with this aspect use allergen extracts as stimulus. Under natural exposure conditions, however, the bioavailability of allergen depends on allergen liberation from internal binding sites within the allergen carrier, e.g. pollen grains. In comparing total protein and major allergen release from timothy grass (Phleum pratense L.) pollen freshly collected on rural meadows or near high-traffic roads, there was a striking difference between the pollen, with higher allergen release rates from rural meadow pollen grains. Thus, allergen release does not explain the higher prevalence rates of atopic sensitization and disease observed in many epidemiological studies in children exposed to automobile exhaust. Therefore, other possible effectors from pollen grains were investigated. Pollen grains incubated in protein- free buffer were found to secrete significant amounts of eicosanoid-like substances, namely leukotriene (LT) B(4)-like and prostaglandin E(2)-like substances, in a pH-, time- and temperature-dependent fashion. The highest values of eicosanoid secretion were found in birch, grass and mugwort pollen, while pine (Pinus sylvestris L.) pollen showed only marginal eicosanoid-like secretion. Additionally, the release of these substances was significantly higher from pollen which had been collected near roads with heavy traffic, indicating a stronger proinflammatory activity of these pollen grains. In order to investigate the effects of air pollutants, native pollen grains were exposed in a dose- and time-dependent fashion in a fluidized bed reactor to traffic-related pollutants, e.g. volatile organic compounds (toluene, m-xylene), leading again to a significant increase in the secretion of LTB(4)-like immunoreactivity, in contrast to exposure with sulfur dioxide. This finding opens a new dimension of understanding of the early events in allergic sensitization, indicating that proinflammatory effects of the allergen carrier, e.g. the pollen grain itself, can lead to activation of the mucosal membrane. These findings might help to also explain the higher prevalence rates of pollen allergy in areas with high automobile exhaust emissions. Furthermore, the allergenic 'potency' of various allergens has to be redefined at the allergen carrier level with regard to different stages of allergen and mediator release prior to the contact with the host's immune system.

Air Pollution↗

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Air pollution and allergy: experimental studies on modulation of allergen release from pollen by air pollutants.

The fact that allergic diseases increase in prevalence is a generally accepted and worldwide phenomenon. The causes for this increase are not known: only hypothetical concepts exist. Epidemiological studies comparing Eastern and Western European populations have shown a striking difference in the prevalence of respiratory atopic diseases, which is lower in the East. At the same time, different patterns of air pollution have been described, namely 'classical' type I, characterized by SO2 and dust prevailing in the East, and 'modern' type II, characterized by organic compounds, fine particles and ozone, which is more prominent in the West. Type II was associated in multivariate regression analysis with increased prevalence of IgE-mediated allergy. Pollen grains collected from industrial regions with high polyaromatic hydrocarbon load in West Germany, but not in East Germany, were shown to be agglomerated with airborne particles. In vitro exposure of pollen to particles indicated morphological changes and increased allergen release from the pollen. In vitro exposure of pollen to gaseous pollutants (SO2 and NO2) under different conditions of humidity resulted in SO2-induced, but not NO2-induced reduction of allergen release from pollen. It is concluded that the bioavailability of grass pollen allergens may be modulated by air pollutants, supporting the concept of an interaction between pollen and pollutants in the atmosphere outside the organism which in turn may affect allergy-relevant phenomena.

Air Pollutants↗

PubMedDate not supplied

Xenobiotics and food allergy: in vivo and in vitro studies in patients with apple allergy.

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Adult↗

PubMedDate not supplied

What makes a child allergic? Analysis of risk factors for allergic sensitization in preschool children from East and West Germany.

Earlier epidemiologic studies within Germany found a higher frequency of allergic sensitization in West Germany. The reasons for that and the role of environmental factors in the process of allergic sensitization are not fully understood. This study aimed to determine the prevalence of positive skin-prick test results 5 years after unification and to investigate risk factors for allergic sensitization in preschool children. A total of 1235 children (5-6 years) from two West and five East German locations were skin-prick tested after the compulsory school entrance examination. Six common aero- (birch, grass, mugwort pollen, cat, HDM, alternaria) and two food allergens (egg, milk) were used and additional information was obtained by questionnaire. Of the tested children 23.3% exhibited at least one positive reaction. The prevalence of sensitization to the single allergens was as follows: grass (14.4%), birch (6.6%), mugwort pollen (4.5%), cat (8.5%), HDM (5.5%), alternaria (4.9%), egg (2.8%), and milk (3.9%). In the crude analysis significantly more children were sensitized in the East German city Magdeburg (40.2%) compared to the West German control region Borken (23.5%) (OR 2.20, CI 1.47-3.29). Dampness and visible molds were reported in 8.8% of all households, but significantly more often for East German apartments (10.3% versus West Germany 1.9%, OR 5.85, CI 2.55-16.53). Dampness and molds were associated with a higher frequency of sensitizations (40.6% versus 27.6% in unaffected homes). After controlling for sex, parental atopy, SES, family size, and smoking during pregnancy, this association remained statistically significant (OR 1.93, CI 1.19-3.12). With regard to single allergens, dampness and visible molds were significantly associated with sensitization to HDM (OR 3.37, CI 1.63-6.96), cat (OR 3.19, CI 1.11-5.74), and mugwort pollen (OR 2.86, CI 1.29-6.35). In addition, family size was inversely and linearly associated with the frequency of sensitization (OR for four, three, and two-person households: 1.10 (0.74-1.63), 1.57 (1.06-2.42), 2.70 (1.39-5.24), respectively, when compared to family size of five or more). Neither parental predisposition for atopic diseases nor parental education level influenced the prick test reactivity. We conclude that in addition to genetic predisposition, environmental factors like indoor climate and probably infectious stimuli (family size) play an important role in the process of allergic sensitization in children.

Allergens↗