Antitumor activity of purified cell walls from Corynebacterium parvum

Cell walls (CW), containing peptidoglycan and carbohydrate, were prepared from Corynebacterium parvum and tested for lymphoreticular stimulation and antitumor effects in CBA-T6T6 mice. CW did not induce splenomegaly. Peritoneal macrophages became cytostatic to Rl leukemia cells in vitro after ip injection of CW or of peptidoglycan but not of carbohydrate; however, on a dry-weight basis the activity was low (less than 10%) compared with that of C. parvum. Tumor outgrowth was significantly suppressed after sc injection of mixture of M4 fibrosarcoma cells and CW, but again the activity of CW was less than 10% of the of C. parvum. In contrast to injection of C. parvum, intratumor injection of CW failed to retard tumor growth in normal mice, although a suppressive effect was found in mice presensitized to C. parvum. Again, unlike C. parvum, CW did not act as an adjuvant for tumor-specific transplantation antigen, as judged by a lack of enhanced resistance to tumor challenge after injection of mixtures of CW and irradiated M4 cells. The distribution and persistence of 125l-labeled C. parvum and CW after sc or ip injection were similar. CW activity was not restored by attachment to oil droplets or emulsification in Freund's incomplete adjuvant.