Effects of lipopolysaccharides on human dental pulp cells.

Human dental pulp cells were treated with 1, 10, and 100 micrograms/ml of lipopolysaccharide (LPS). The effects of treatment were examined by measurement of the DNA content, protein content, and alkaline phosphatase activity of the cells. LPS samples were purified from Porphyromonas gingivalis, Porphyromonas endodontalis, and Fusobacterium nucleatum isolated from root canals, and Escherichia coli 0111:B4 LPS was used as a positive control. At a concentration of 1 microgram/ml, none of the LPSs caused any change in the production of DNA or protein, whereas the amount of DNA was increased at 10 micrograms/ml and inhibited at 100 micrograms/ml. Protein synthesis was decreased by LPSs at both 10 and 100 micrograms/ml. Alkaline phosphatase activity was not changed at any concentration of LPS tested.