Antitumor activity of Klebsiella 03 lipopolysaccharide in mice

The antitumor activity of Klebsiella 03 lipopolysaccharide (KO3 LPS) isolated from the culture supernatant against S180 sarcoma, Ehrlich carcinoma, MM2 mammary carcinoma and Meth A fibrosarcoma in mice was investigated. KO3 LPS significantly prolonged the lifespan of S180-bearing ddY mice and MM2-bearing C3H/He mice by intraperitoneal pre- or postmedication at doses ranging from 0.1 to 1.0 mg/kg. The LPS also inhibited the growth of subcutaneously inoculated Ehrlich carcinoma in ddY mice and Meth A sarcoma in BALB/c mice by intraperitoneal, intravenous or intratumoral administration. The intratumoral injection of KO3 LPS was most effective and results by the intravenous and the intraperitoneal administrations followed in effectiveness, but the administration through the subcutaneous route was hardly effective. Thus, KO3 LPS was shown to have antitumor activity on both allogeneic tumors and syngeneic tumors. It was also indicated in this study that the lifeprolonging effect of KO3 LPS on S180 ascites type tumor-bearing mice was significantly minimized by pretreatment of cyclophosphamide and that the LPS did not influence the cell viability of HeLa cells, Ehrlich cells and MM2 cells in vitro. These results suggest that the antitumor activity of KO3 LPS is provided by host-mediated actions.