Studies on inflammation in mice: dynamics of inflammatory response induced by extract from Escherichia coli and influence of antiinflammatory drugs.

The intraperitoneal injection of E. coli extract in the mouse resulted in a biphasic accumulation of leukocytes. The first phase of leukocyte accumulation was based on neutrophil influx in the peritoneal cavity, which occurred 1-2 days after E. coli extract administration. The second phase was based on macrophage influx, which occurred 12 days after E. coli extract administration. Preceding the influx of neutrophils in the first phase, the exudation of plasma proteins in the peritoneal fluid occurred at 4 h. A slight increase in plasma exudation accompanied the macrophage influx in the second phase of leukocyte accumulation. These kinetics of the inflammatory response to E. coli extract were similar to those of the inflammatory response to lipopolysaccharide (LPS), suggesting that the inflammatory response induced by E. coli extract administration was mainly due to the effect of LPS, a component of the E. coli extract. Indomethacin reduced the plasma exudation at 4 h but had no influence on the leukocyte accumulation. On the other hand, dexamethasone suppressed the leukocyte accumulation in both phases.