Nuclear antigens reacted with sera and ascites of hepatocellular carcinoma patients

In order to study hepatocellular carcinoma-associated antigens, screening of sera and ascites was done from hepatocellular carcinoma patients having antibodies reactive with three hepatocellular carcinoma cell lines (PLC/PRF/5, Hep 3B and HA22T/VGH). The indirect immunofluorescent antibody test was used. Ten of 86 (11.6%) sera and 3 of 14 (21.4%) ascites from hepatocellular carcinoma patients showed positive bindings, whereas only 1 of 35 (2.8%) sera, none of 4 (0%) ascites from chronic hepatitis patients and 3 of 60 (5%) normal human sera had positive immunofluorescent antibody activity. The binding specificities of these positive specimens were further defined by other human cancer cell lines and mouse NIH/3T3 fibroblasts. The antinuclear antibody test against mouse liver sections was also performed. The results suggested that antigens identified by the two tests may not be identical. The nature of nuclear antigens reactive with one of the serum samples, S83, and ascites A83 were characterized. These antigens were sensitive to trypsin but not to RNase A and DNase I. Further studies by radioimmunoprecipitation and two-dimensional gel electrophoresis with serum S83 and ascites A83 showed two acidic phosphorylated antigens with molecular weights of 77 and 79 kd, which had a pI around pH 5.2. The presence of a large amount of these two phosphorylated proteins in 5 of 7 human hepatocellular carcinoma cell lines suggests that these two antigens might play some roles in the carcinogenesis or progression of human hepatocellular carcinoma.