Placental Lipopolysaccharide Enhances Macrophage Activation

The purpose of this study was to assess the effect of human placental lipopolysaccharide (HP-LPS) on activation of macrophages. We isolated and characterized the lipopolysaccharide from human placenta and E. coli by Westphal's method. The effects of different concentrations of E. coli and HP- LPS were assayed on mice macrophages and nitric oxide production was measured using Griess's method; data were then analyzed. Results showed that using the Westphal method, HP- LPS could be isolated as well as Gram-negative bacterial LPS. The results indicate that the HP- LPS had ability to stimulate mice macrophages to produce nitric oxide. Detoxified LPS Gram-negative bacteria in concentrations of more than 500 ng/ml showed toxicity. Whereas, HP- LPS at concentration of 1000 ng/ml had a significant effect on nitric oxide production. In addition, the isolated HP- LPS had no pyrogenic effects. The findings of this study suggest that the HP- LPS shows activity similar to Gram- negative bacterial endotoxin which stimulates macrophages to produce nitric oxide. These properties indicate that this substance acts as a detoxified Gram-negative bacterial endotoxin. Because of its human origin, it has no toxic effects and may be a safe adjuvant.