An Analysis of the Increase in Host Resistance to Isogenic Tumor Invasion in Mice by Treatment with Corynebacterium parvum

Abstract

This study deals with the effects of Corynebacterium parvum on the resistance of the host to transplantable isogenic tumors. Differences have been observed depending on the nature of the tumor, the size of the inoculum, the mode of introduction, and the time interval between the tumor inoculum and the treatment with C. parvum.

In the case of the YC8 Balb/c isogenic lymphoma, remarkable results were obtained when both malignant inoculum and C. parvum were applied intraperitoneally. The results were still consistent, although less favorable, when the malignant challenge and the immunostimulator were administered intravenously. In this experimental model, visceral metastases affecting the lung, liver, kidney, and spleen were frequently observed in the control animals. Treatment with C. parvum produced a remarkable inhibition of the metastasic dissemination.

The resistance of F₁ (Balb/c × C₅₇B1) hybrid hosts to the invasion of YC8 lymphoma was not consistently different from the resistance of the parental Balb/c strain. Treatment with C. parvum did not significantly increase the resistance of the F₁ hybrids against tumor dissemination, a finding at variance with that previously reported for AKR leukemia.

The effects of C. parvum on the evolution of the isogenic Graffi tumor were less favorable than the effect on YC8 lymphoma. It follows from the results reported here that the enhancement of resistance of the host against isogenic tumors by C. parvum is conditioned by a variety of factors, such as the nature of the tumor, the route of inoculation, and the time interval between the treatment and the tumor challenge. There is clearly a need for further experimentation to find optimal conditions of administration of C. parvum for the extension of these data to human applications.