ROLE OF ENDOTOXIN IN TUMOR-NECROSIS-FACTOR-ALPHA EXPRESSION FROM ALVEOLAR MACROPHAGES TREATED WITH URBAN AIR PARTICLES

The effects of urban air and diesel particles on inflammatory cytokine gene expression, tumor necrosis factor alpha (TNF-alpha) in particula r, were studied in rat alveolar macrophages. TNF-alpha, interleukin (I L)-1, IL-6, cytokine-induced neutrophil chemoattractant (CINC), and ma crophage inflammatory protein (MIP)-2 gene expression and TNF-alpha se cretion were increased in cells treated with 50 to 200 mu g/mL of urba n air particles in a concentration-related manner. There was no cytoki ne induction by diesel particles at any of the concentrations tested. Cytokine expression was not related to reactive oxygen species since a ntioxidants, such as catalase, TMTU, or DMSO, had not effect on TNF-al pha secretion. However, cytokine induction by urban air particles was completely prevented by polymyxin B, an antibiotic capable of neutrali zing bacterial lipopolysaccharide (LPS) activities. Furthermore, LPS w as detected on the urban air particles, but not on diesel particle. Th ese results suggest that activation of cytokine gene expression and se cretion in rat alveolar macrophages by urban air particles is due to t he presence of endotoxin on the particles.