IMMUNOHISTOCHEMICAL DETECTION OF THE NS4 ANTIGEN OF HEPATITIS-C VIRUSAND ITS RELATION TO HISTOPATHOLOGY

The immunohistochemical localization of the hepatitis C virus (HCV) no nstructural antigen 4 (NS4) was investigated in formalin-fixed human l iver biopsy samples taken from 10 patients who were anti-HCV positive. NS4 was detected within the cytoplasm of hepatocytes in all HCV-posit ive patients studied, but not in the mononuclear cell infiltrates, bil e duct epithelium, or endothelial cells. A high proportion of hepatocy tes appeared positive, but the staining intensity was variable. After a coded histological evaluation of the liver tissue, the pattern of li ver injury was shown to have no significant correlation with antigen-p ositive hepatocytes, and no direct relationship was observed between t he distribution of antigen-positive hepatocytes and areas of hepatocyt e necrosis. ne staining pattern was considered to be specific because liver samples from patients chronically infected with hepatitis B viru s or from uninfected individuals were negative. Furthermore, no staini ng as noted when either preimmune rabbit serum or anti-NS4 adsorbed ag ainst the specific synthetic peptide was substituted for the primary a ntibody.