Enhanced polychlorinated biphenyl lesions in Moloney leukemia virus-infected mice.

The hepatic toxicity produced by polychlorinated biphenyls (PCB) was enhanced in mice that were inoculated with an oncogenic virus, Moloney leukemia virus (MLV). Whenever there was neoplastic involvement of the spleen by MLV, the hepatic lesions produced by PCB were more pronounced than in those of non-MLV inoculated mice. Mice were exposed to PCB Aroclors, 1254, 1242, and 1221 for six months. Aroclors 1254 and 1242 were hepatotoxic with Aroclor 1254 causing death. Aroclor 1221 did not affect the mice. Liver weights in mice that were fed PCBs for six months and then maintained on a PCB-free diet for an additional three months were comparable with those of non-PCB exposed mice. These results suggest that the PCB-produced hepatic lesions (noncirrhotic) regenerate after removal of PCB from the diet. Polychlorinated biphenyls did not affect (promote or induce) the oncogenesis of MLV in this study.