Liver-specific F antigen in the serum of patients with liver diseases and the detection of early stage hepatocellular carcinoma.

Liver-specific F antigen was detected in serum using human-specific guinea pig antiserum, in 75 out of 121 patients with various liver diseases. The antigen was detectable in most of the patients (86.7%) with hepatocellular carcinoma, and the levels of F antigen were often high in these patients. There was no correlation between the levels of F antigen and alpha-fetoprotein. Temporal changes of serum F antigen level were also studied in patients with hepatocellular carcinoma. In 8 out of 13 patients with hepatocellular carcinoma, serum F antigen level remained continuously high, and in these patients, it had been significantly high for several months to one year before hepatocellular carcinoma became clinically detectable. Extracts of hepatocellular carcinomas obtained by necropsy was examined for the presence of F antigen, and it was found that most of hepatocellular carcinomas contained the human-specific determinant of F antigen, but lacked the species non-specific determinant of the antigen. The use of human-specific anti-F antiserum may facilitate early detection of hepatocellular carcinoma in some patients.