Effect of BCG on hepatocarcinogenesis of the rat induced by 3'-methyl-4-(dimethylamino)azobenzene.

The effect of BCG, an immunopotentiator, on the hepatocarcinogenesis of the rat induced by 3'-methyl-4-(dimethylamino)azobenzene (3'-Me-DAB) was investigated. After administration of 3'-Me-DAB for 6 weeks, BCG was injected to the rats at 2-week intervals for 50 weeks and the serial determinations of serum alpha-fetoprotein and morphological examination of the liver were made. In the control group, the second rise of serum alpha-fetoprotein, which reflected the occurrence of hepatoma, was seen at about 12 weeks after discontinuance of 3'-Me-DAB. On the other hand, the second rise of serum alpha-fetoprotein in the group treated with BCG was delayed about 10 weeks compared to control group, although there was no significant difference in the final incidence of hepatomas between these two groups. Infiltration of the lymphocytes was observed in the liver of rats treated with BCG without hepatoma. BCG seems to have an inhibitory effect on 3'-Me-DAB carcinogenesis of the rat, possibly by stimulating the cell-mediated immunity, although it is not strong enough to prevent the occurrence of hepatoma completely.