The in vitro effect of Actinobacillus actinomycetemcomitans strain Y4 lipopolysaccharide on murine peritoneal macrophages

Abstract

A. actinomycetemcomitans strain Y4 lipopolysaccharide (LPS) was examined for its in vitro effect on murine peritoneal macrophage morphology, viability and lysosomal enzyme activity. Addition of 50 .mu.g of Y4 LPS/106 macrophages resulted in macrophage activation, eliciting release of acid phosphates (AsP) and accumulation of intracellular AcP without a loss in viability. There was also an increase in the number of organelles and cell surface ruffles. Addition of 100 250 .mu.g of Y4 LPS caused flattening, rounding and blebbing of the cell surface and release of large quantities of AcP and lactate dehydrogenase within 5 min of exposure. Alteration of cell ultrastructure occurred within 30 min and extensive autophagocytosis by 24 h, indicative of cell injury. Short-term (< 24 h) experiments appear necessary to distinguish between the effects of cell activation and cell death caused by A. actinomycetemcomitans Y4 LPS.