Synergistic induction of tumor necrosis factor ? by bacterial lipopolysaccharide and lipoteichoic acid in combination with polytetrafluoroethylene particles in a murine macrophage cell line RAW 264.7

Abstract

The induction of tumor necrosis factor alpha (TNF-alpha) by polytetrafluoroethylene (PTFE) particles (5-50 microns) and by bacterial lipopolysaccharide (LPS) and lipoteichoic acid (LTA) was examined in RAW cell cultures. Twenty-four-hour culture supernatants from the treated and control cells were assayed for TNF-alpha using a mouse L929 cell cytotoxicity assay. Untreated RAW cells produced low levels of endogenous TNF-alpha in the culture supernatants. Addition of 0.5 ng to 1 microgram/ mL LPS or 1 ng to 1 microgram/ml LTA increased the TNF-alpha production by 7-3570-fold and 2-815-fold, respectively. Addition of 1-5 mg PTFE increased the TNF-alpha production by 6-17-fold over the untreated control cell levels. The cells exposed to PTFE and 0.5 ng/mL LPS or 5 ng/mL LTA produced TNF-alpha levels that were significantly higher than those produced by any inducer alone. Thus, both LTA, a Gram-positive bacterial cell wall component and LPS, a Gram-negative bacterial cell wall component, can induce TNF-alpha production, which is further enhanced by PTFE particles in RAW cells.