Bernard Halpern

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

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.

Nonspecific Cytotoxic Activity of Peritoneal Exudate Cells against Isogenic Tumoral Cells in Animals Treated with Corynebacterium parvum

Peritoneal exudate cells obtained from animals treated with Corynebacterium parvum displayed a cytotoxic action on YC8 isogenic tumoral cells as evidenced by the 51 Cr-release method. It was found that the cytotoxic effect was shared by nonadherent and adherent cells. In this respect, the adherent cells were more active (by a factor of about two) than the nonadherent cells. The induction of the cytotoxic effects of the peritoneal exudate lymphocytes appears to be due to the proper action of C. parvum and independent of the presence of the tumor, since no difference in the cytotoxic potency was observed between control and tumor-bearing animals.

Inhibition of Thymidine Incorporation of Tumoral YC8 Cells Cultured in Vitro by Peritoneal Macrophages Activated with Corynebacterium parvum

Peritoneal cavity macrophages obtained from animals treated with Corynebacterium parvum inhibited the DNA synthesis of isogenic YC8 tumoral cells present in the culture to a considerable extent. Macrophages from control animals displayed a similar activity, but at a much lower level. Previous x-irradiation of the macrophages did not abolish their inhibitory activity.