Mchanisms of antitumor action of Corynebacterium parvum: nonspecific tumor cell destruction at site of immunologically mediated sensitivity reaction to C. parvum.

Mice immunized in the footpad with Corynebacterium parvum developed a systemic mechanism with a potential for destroying syngeneic tumor cells. The development of this mechanism of antitumor action depended on the generation of a state of systemic sensitivity to C. parvum antigens, which allowed an immunologically mediated inflammatory response to be focused at the site of a tumor cell challenge or in the bed of an established tumor. This resulted in complete inhibition of growth of the former regression of the latter. This nonspecific mechanism of tumor cell destruction could be utilized only during a relatively short period when mice were responding maximally to the organism. This corresponded to a period during which there was maximum cell division in the lymph node draining the site of immunization with C. parvum, maximum systemic macrophage activation, and maximum sensitivity to eliciting injections of the organism. The potential for destroying tumor cells could be transferred to normal recipients with lymph node cells from C. parvum-immunized donors, which indicated the distinct possibility that antitumor action was based on the cell-mediated response to C. parvum antigens. That the destruction of tumor cells at the site of a C. parvum sensitivity reaction was associated with a massive influx of mono-nuclear cells provided further support for this possibility.