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To identify the size and components related to toxicity of ambient particles, we used a trichotomous impactor to collect 17 sets of particles in three size ranges--submicrometer (diameters < 1 microm; PM1.0, fine (diameters between 1 and 2.5 microm; PM1.0-2.5, and coarse (diameters between 2.5 and 10 microm; PM2.5-10--at stations monitoring background, urban, traffic, and industrial air in Taiwan. Elemental contents, carbon contents, soluble ions, and endotoxin content of particles were determined by X-ray fluorescence spectrometry, thermal analysis, ion chromatography, and the Limulus amebocyte lysate assay, respectively. Human bronchial epithelial BEAS-2B cells were exposed to particle extracts at 100 micro g/mL for 8 hr, and interleukin-8 (IL-8) concentrations in the medium and lipid peroxidation products were measured. Particle-induced tumor necrosis factor-alpha (TNF-alpha) production by mouse macrophage RAW 264.7 cells was also measured. PM1.0 stimulation resulted in significantly higher IL-8 production and lipid peroxidation than PM2.5-10, whereas the responses elicited by PM1.0-2.5 were not significantly higher than blank filters. Untreated and polymyxin B-pretreated PM1.0 also stimulated more TNF-alpha production by RAW 264.7 cells than PM2.5-10 and PM1.0-2.5. Cytokine production was significantly associated with metal contents of PM1.0: IL-8 correlated with Cr and Mn, and TNF-alpha correlated with Fe and Cr. Lipid peroxidation in BEAS-2B cells correlated with elemental and organic carbon contents. Our study found that size and composition of ambient particles were both important factors in inducing cytokine production and lipid peroxidation.
Huang et al. (Fri,) studied this question.