In vitro fibrinolytic activity and viability of rat alveolar macrophages treated with inflammation generating mineral dusts.

Rat alvolar macrophages demonstrated plasminogen dependent fibrinolysis in vitro which was inhibited to varying degrees by the addition of zymosan, the non-toxic particulate titanium dioxide, and the toxic dusts quartz and chrysotile asbestos. Assessment of viability suggested that the inhibition produced by zymosan and titanium dioxide could be accounted for by cytotoxic effects but in the case of quartz and chrysotile asbestos there was evidence that stimulation of fibrinolysis preceded cell death. Zymosan, which caused no observeable enhancement of alveolar macrophage fibrinolysis was found to markedly stimulate peritoneal macrophage fibrinolysis. The choice of assays of cell function to assess the action of toxic dusts are discussed.