Immune and enzyme histochemical studies of a human hepatocellular carcinoma cell line producing hepatitis B surface antigen.

PLC/PRF/5, a tissue culture cell line derived from a human hepatocellular carcinoma and producing hepatitis B surface antigen (HBsAg), was studied by immune and enzyme histochemical techniques. HBsAg was demonstrated in the cytoplasm and on the surface of tumor cells. The percentage of HBsAg-positive cells in subculture increased with time until almost all cells expressed HBsAg when the monolayer reached confluence. Similar patterns were found for alpha 1-anti-trypsin and carcino-embryonic antigen, whereas alpha-fetoprotein was observed only in small foci of cells. Hepatitis B core antigen and albumin were not detected. gamma-Glutamyl transferase activity was markedly increased in the tumor cells, whereas adenosine triphosphatase and glucose-6-phosphatase activities were not demonstrable. Patterns of antigenic expression and enzyme phenotype of PLC/PRF/5 cells show remarkable resemblance to those observed in vivo in human hepatocellular carcinoma. Therefore, this cell line may be a useful model to study the control and modulation of both oncofetal antigens and HBsAg.