Airborne endotoxin exposure and the development of airway antigen-specific allergic responses.

BACKGROUND AND OBJECTIVE: Repeated exposure of aerosolized antigen via respiratory tract can induce immunoglobulin (Ig) E isotype-specific tolerance to this antigen. However, the atopic individuals often produce a higher titre of IgE in response to airborne environmental allergens. The mechanisms of this differential regulation of airway allergen-specific immune responses are not fully understood. This study investigated the role of airborne endotoxin on the initiation of antigen-specific airway allergic responses. METHODS: ELISA methods for detection of isotypes of antigen-specific antibodies and competitive reverse transcription polymerase chain reaction for detection mRNA of cytokines were used. In addition, Liu stain method was used to analyse the amounts of eosinophils in bronchoalveolar lavage fluid. RESULTS: Mice pre-exposed with airborne endotoxin mounted significantly higher amounts of OVA-specific IgE antibody responses to inhaled OVA than those OVA-only sensitized mice. Inhaled endotoxin could downregulate repeated airway antigen exposure-induced IgE isotype-specific tolerance and increase antigen-induced lung eosinophils infiltration. CONCLUSIONS: These data show that airborne endotoxin exposure could potentiate allergen-specific airway inflammation. The results should have potential implications for understanding the development of allergen-induced airway allergic responses.

Indoor endotoxin and glucan in association with airway inflammation and systemic symptoms.

Indoor bioaerosols (i.e., bacteria, fungi, endotoxin, and beta-1,3-glucan) were determined in daycare centers, office buildings, and domestic environments in the Taipei area. In addition, we used a questionnaire survey to determine associations between indoor dampness, bioaerosols, and airway inflammation and systemic symptoms. We demonstrated that the median levels of indoor bacteria and fungi were the highest in daycare centers, followed by those in homes and office buildings. Similar patterns were observed for endotoxin and beta-1,3-glucan. The prevalences of airway inflammation and systemic symptoms were higher for females in office buildings than for employees in daycare centers; all symptoms were more prevalent in females than males. With respect to the relationship between bioaerosol exposure and airway inflammation and systemic symptoms, we found a strong association between beta-1,3-glucan and lethargy/fatigue.

An airbone mold-derived product, beta-1,3-D-glucan, potentiates airway allergic responses.

Repeated inhalation of allergen leads to the down-regulation of allergen-specific IgE responses in non-atopic individuals as well as in mice. This phenomenon is named inhalation-induced IgE tolerance. In contrast, inhaled allergen causes significant IgE and allergic responses in atopic persons. The mechanisms involved in this differential regulation of airway allergen-specific immune responses remain unclear. Besides the allergen exposure of genetically susceptible individuals, environmental contamination is considered to play a role as an initiating factor for airway allergic responses. Using a murine model, we demonstrate here that airborne beta-1, 3-D-glucan, which exists frequently in our environment, particularly in highly humid areas, can abrogate inhalation-induced IgE isotype-specific down-regulation and promote airway eosinophil infiltration to inhaled antigen.

Dampness and airway inflammation and systemic symptoms in office building workers.

To evaluate dose-response relationships between airway inflammation/systemic symptoms and dampness exposure, we conducted a self-reported questionnaire study on risk factors among 1237 employees in 19 air-conditioned office buildings in the Taipei area. The odds ratio for eye irritation was 1.34 when either stuffy odor or mold was present in the buildings. The odds ratio increased to 1.72 when both stuffy odor and mold were present, to 3.14 when water damage was also present, and to 5.03 when four dampness exposure factors were present. Dampness in the building had a dose-response effect on eye irritation, cough, and lethargy/fatigue.

Peasant flood in China: internal migration and its policy determinants.

PIP: A survey was undertaken by the Chinese Academy of Sciences in 1986 to explore the composition and patterns of rural population movements. 230 villages were selected from 84 townships in 59 counties scattered across 11 regions. Because of incomplete information, only data for 222 villages were used. Population flows were classified into: 1) intramigration or intraflow within the boundaries of their own townships; 2) out-migration, emigration, or outflow involving those who left the townships; and 3) in-migration, immigration, or inflow that affected those who moved into the 222 villages from outside. Age, sex, education, postmigration occupation, and duration of stay details were obtained for every migrant. Some 43,223 persons were involved in intraflows and 26,993 emigrated from the surveyed townships in 1986. The volume of internal migration in China seemed to be related to the distance between the origins and destinations of migrants. Among 70,216 migrants, about 74% were males and only 26% were females. Over 57.38% of the migrants from 222 villages shifted into industrial (34.31%) and construction (23.07%) activities. The service sector (food providers, stall holders, door-to-door retailers, barbers, and small shops) attracted 9.73%. Only 565 were engaged in cropping and 1614 in forestry, animal husbandry, sideline production, and fishery. As to age groups, 1688 (2.4%) were aged 17 years or under, 61,530 (88%) were aged 18-45, and 6999 (9.9%) were 46 years old or older. In 1986 seasonal migrants accounted for some 80% of all emigrants from the surveyed villages. Education did not play a significant role in promoting migration in the mid-1980s. 39% of the labor force had received primary education and the same percentage of out-migrants had acquired primary school education. The younger the age group, the more of them tended to move away from home: for those aged 17 or under if 100 persons migrated within the township, 113 moved out of town. A nationwide network should be established to provide information for migrants regarding their rights and obligations, job prospects, and cultural differences.^ieng