The antitumor activity of a mixed bacterial vaccine against mouse hepatoma

Mixed bacterial vaccine (MBV), derived from heat-killer Streptococcic pyogenes and Serratia marcescens, is a biological response modifier. In our study MBV prolonged the survival of mice with ascitic hepatoma significantly, being 18.5 �� 1.0 d (intraperitoneal injection, ip) and 18.8 �� 1.5 d (subcutaneous injection, sc) versus 16.7 �� 1.0 d as compared to the control, and suppressed the growth of subcutaneous nodule of hepatoma markedly, being 1.9 �� 0.2 g (ip) and 1.7 �� 0.3 g (sc) versus 2.3 �� 0.7 g as compared to the control. Subcutaneous usage of MBV increased the infiltration of mononuclear cells into tumor, whereas intraperitoneal usage of MBV did not. Splenomegaly was observed after treatment of hepatoma bearing mice by using MBV either subcutaneously or intraperitoneally. The above data demonstrated that MBV is a potential immunostimulant, which could be used in tumor biotherapy. These data also helped further elucidate the mechanism of MBV against tumor.