Inflammatory cell recruitment as a measure of mineral dust toxicity

The cellular inflammatory response has been assessed following intra-peritoneal injection of mineral dusts in mice. To calibrate the system, dusts of known pathogenicities were injected at 50, 500 or 2500μg/animal, and the inflammatory response assessed at 2, 4 and 8 days; inflammation was measured as total cells recovered by peritoneal lavage, differential cell count and macrophage activation status. The cellular response was found to be highly sensitive, since a transient response could be detected following injection of saline alone. Using standard dust preparations, titanium dioxide was found to be relatively inactive while quartz and chrysotile asbestos induced a marked inflammatory response. There was some evidence that the cell yield was influenced by macrophage adherence and possibly direct cytotoxicity, and the dose response was consequently not linear. Further work is planned to systematically examine this aspect. Two other particulates were examined in the test system — a respirable coal mine dust and an aramid fibre preparation. The response to the coal mine dust was small while aramid fibre induced a considerable sustained inflammatory reaction. We conclude that the mouse peritoneal cavity can provide a rapid, simple and reliable in vivo test of the potential pathogenicity of particulate material.