Background: The organic chemicals present in Asian sand dust (ASD) might contribute to the aggravation of lung\neosinophila. Therefore, the aggravating effects of the Tar fraction from ASD on ovalbumin (OVA)-induced lung\neosinophilia were investigated.\nMethods: The Tar fraction was extracted from ASD collected from the atmosphere in Fukuoka, Japan. ASD\ncollected from the Gobi desert was heated at 360�°C to inactivate toxic organic substances (H-ASD). ICR mice were\ninstilled intratracheally with 12 different test samples prepared with Tar (1 ?g and 5 ?g), H-ASD, and OVA in a\nnormal saline solution containing 0.02% Tween 80. The lung pathology, cytological profiles in the bronchoalveolar\nlavage fluid (BALF), inflammatory cytokines/chemokines in BALF and OVA-specific immunoglobulin in serum were\ninvestigated.\nResults: Several kinds of polycyclic aromatic hydrocarbons (PAHs) were detected in the Tar sample. H-ASD + Tar\n5 ?g induced slight neutrophilic lung inflammation. In the presence of OVA, Tar 5 ?g increased the level of\neosinophils slightly and induced trace levels of Th2 cytokines IL-5 and IL-13 in BALF. Also mild to moderate goblet\ncell proliferation and mild infiltration of eosinophils in the submucosa of airway were observed. These pathological\nchanges caused by H-ASD + OVA were relatively small. However, in the presence of OVA and H-ASD, Tar, at as low\na level as 1 ?g, induced severe eosinophil infiltration and proliferation of goblet cells in the airways and significantly\nincreased Th2 cytokines IL-5 and IL-13 in BALF. The mixture showed an adjuvant effect on OVA-specific IgG1\nproduction.\nConclusions: These results indicate that H-ASD with even low levels of Tar exacerbates OVA-induced lung\neosinophilia via increases of Th2-mediated cytokines. These results suggest that ASD-bound PAHs might contribute\nto the aggravation of lung eosinophila.
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