Prophylactic effect of BCG cell-wall skeleton on the tumor induction by 7,12-dimethylbenz[a]anthracene in mice: strain difference.

Prophylactic effect of repeated intravenous administrations of oil-attached BCG cell-wall skeleton (BCG-CWS) on the induction of tumor by 7,12-dimethylbenz[a]anthracene (DMBA) was investigated in various strains of mice. The subcutaneous injection of DMBA emulsified in oil induced squamous cell carcinoma in almost all of the strains of mice. Treatment of C57BL/6, BALB/c, and ddO strains with BCG-CWS with appropriate route and timing resulted in the retardation of DMBA-induced tumor development manifested by a prolonged latent period of tumor outgrowth. In contrast, the same BCG-CWS treatment of C3H/He and BTK mice was incapable in preventing such DMBA-induced carcinogenesis. Thus, the treatment with BCG-CWS was effective for preventing the DMBA-induced carcinogenesis in certain strains of mice, but the effectiveness varied depending on the strain. The implication of such a strain variationof the BCG-CWS effect on the prophylaxis of chemical carcinogenesis was discussed in the context of differences in the magnitude of immunopotentiation of the host by BCG-CWS.