PubMed1976
BCG (Bacillus Calmette-Guerin) vaccine, Tice strain, caused a threefold increase in spleen weight of normal animals and a fourfold increase in spleen weight of sarcoma-bearing mice. In the latter group, the BCG vaccine caused infiltration of the sarcoma cells into the peritoneum and tumor metastasis in the spleen. Spleen lymphocytes from mice immunized with neuraminidase-treated sarcoma or from mice that had overcome an inoculum (100 cells) and a challenge (10(4) cells) of sarcoma P-1798 were cytotoxic against 51 Cr- or 14C-2-thymidine-labeled sarcoma cells. The serum of these mice enhanced the cytotoxic activity and inhibited the migration of the syngeneic lymphocytes. These serums also inhibited the migration of peritoneal macrophages from guinea pigs immunized with the sarcoma cells. BCG vaccine enhanced the development and growth of sarcoma P-1798; i.e., 50-100 viable sarcoma cells produced solid tumors in 8% of the untreated animals but in 100% of the BCG-treated animals. The serum of BCG-treated sarcoma-bearing animals inhibited the spleen lymphocyte-mediated cytotoxic action. The spleen lymphocytes from the BCG-treated sarcoma-bearing animals had no effect against 51Cr- or 14C-2-thymidine-labelled sarcoma cells. The data indicate that the serum from BCG-treated sarcoma-bearing animals blocks the spleen lymphocyte-mediated cytotoxic activities directed against proliferation and growth of the sarcoma.