Listeria monocytogenes (LM) methanol extract residue of BCG (MER) and BCG cell walls on oil droplets (BCG cw) are used prophylactic and therapeutic agents in immunotherapy of non antigenic tumors. The mechanisms(s) of LM mediated tumor suppression are investigated both in vivo and in vitro in a culture system. By manipulation of the animals (T-cell deficient, treatment with anti mitotic and anti inflammatory agents, blockade of the RES) and separation of various cell sub- populations insight is being gained into the cellular and molecular basis of non-specific tumor cell destruction. Studies in progress and to be initiated will determine the efficacy of each of the agents mentioned alone or in combination with chemotherapy in the experimental treatment of syngeneic tumors. Bibliographic references: Youdim, S. and Brown, D.: Nonspecific Tumor Cell Destruction Mediated by Listeria monocytogenes in vitro. Am. Assoc. for Cancer Research Proc. 16:182,1975.