Immunohistochemical detection of aflatoxin B1-DNA adducts and hepatitis B virus antigens in hepatocellular carcinoma and nontumorous liver tissue.

Monoclonal antibodies recognizing the stable imidazole ring-opened form of the major N7-guanine aflatoxin B1-DNA adduct have been used in competitive enzyme-linked immunosorbent assays (ELISA) and indirect immunofluorescence assays to quantitate adduct levels in liver tissue. Methods were developed in AFB1-treated animals, then applied to paired tumor and nontumor liver tissues of hepatocellular carcinoma patients from Taiwan. An avidin-biotin complex staining method was also used for of the detection of hepatitis B surface (HBsAg) and X (HBxAg) antigens in liver sections. A total of 8 (30%) hepatocellular carcinoma (HCC) samples and 7 (26%) adjacent nontumor liver tissue samples from Taiwan were positive for AFB1-DNA adducts. For HBsAg, 10 (37%) HCC samples and 22 (81%) adjacent nontumorous liver samples were positive, and 9 (33%) HCC samples and 11 (41%) adjacent nontumor liver samples were HBxAg positive. No association with AFB1-DNA adducts was observed for HBsAg and HBxAg. These methods should be useful in determining the role of exposure in the induction of HCC in Taiwan.