Hepatitis B surface antigen and alpha-fetoprotein secreting human primary liver cell cancer in athymic mice.

A human primary liver cancer cell line which retains the property of synthesizing hepatitis B surface antigen has been successfully transplanted into nude (athymic) mice. The morphology of the heterotransplanted tumor is similar to that of a well-differentiated human primary liver cell cancer. It produces hepatitis B surface antigen, but there is no evidence of hepatitis B virion production: Hepatitis B core antigen is not detected in the PLC tissue, and serum is negative for hepatitis B e antigen. The nude mouse exhibits a resistance to the transplantation of the human primary liver cancer cells which can be modified by sublethal total body irradiation, suggesting involvement of an immunologic rejection mechanism. The heterotransplanted primary liver cell cancer also produces alpha-fetoprotein, as did the original tumor in vivo, although this marker was not detected during in vitro cell culture. The serum level of alpha-fetoprotein rises exponentially, enabling quantitative evaluation of tumor growth. The human primary liver cell cancer in nude mice provides an in vivo model for determination of tumor response to chemotherapeutic agents.