Elevated concentrations of serum alpha-fetoprotein in rats with chemically induced liver tumors.

The study was undertaken to determine whether aflatoxin B1 (AFB1)-induced liver tumors in rats produced alpha1-fetoprotein (AFP) and whether the age of the animals would influence such as appearance, a finding suggested by data seen in man. Other liver carcinogens (N-hydroxy-N-2-fluorenylacetamide, N-2-fluorenylacetamide, and diethylnitrosamine) were tested for their ability to induce liver tumors producing AFP. The presence of AFP. The presence of AFP in the serum was determined by double diffusion in agarose and by comparison also by quantitative radioimmunoassay. Using double diffusion, AFP was detected in the majority of tumor-bearing rats that had received either N-2-fluorenylacetamide or N-hydroxy-N-2-fluorenylacetamide. Sera of diethylinitrosamine-treated rats with liver tumors were all positive, whereas sera of rats bearing AFB1-induced tumors were positive in only a few cases. However, all sera of tumor-bearing rats examined had elevated AFP levels by radioimmunoassay. Nonetheless, the average level of AFP in the sera of rats bearing AFB1-induced tumors was considerably lower, compared to the sera of rats with tumors caused by diethylnitrosamine, N-2-fluorenylacetamide, or N-hydroxy-N2-fluorenylacetamide. Rats started on AFB1 when 6 weeks old had more mixed liver tumors with neoplastic hepatocytes and bile ducts and higher AFP levels than did rats started at 26 weeks of age. However, the histological grade of differentiation of inducted tumors did not seem to influence the AFP level.