Immunohistochemical demonstration of hepatitis B core and surface antigens in paraffin sections

An immunohistochemical staining to demonstrate the hepatitis B core and surface antigens (HBc&sAg) on formalin-fixed, paraffin-embedded liver tissue was investigated. The staining is believed to be valid for the reasons that: (1) HBc&s AG-positive and control tissues were properly selected. (2) The immunospecificities of the antisera to HBc Ag or HBs Ag were verified by immunoelectron microscopy and by conducting the neutralization controls in the staining procedure. (3) The staining results were identical with those shown on unfixed frozen sections from the same cases. The immunoreactive sites of HBc&s Ag are shown to be preserved in the formalin-fixed, paraffin-embedded tissue, and they can be demonstrated by either direct or indirect immunofluorescent and immunoperoxidase methods. The pronase digestion of the tissue sections quenches the nonspecific background staining and thus facilitates the microscopic examination. The indirect immunofluorescent method is more sensitive than the direct. The localization of HBs Ag in liver cells shown by immunohistochemical method is identical with that demonstrated by orcein histochemical stain. The described method demonstrating the HBc Ag in paraffin tissue may offer an additional means in making a specific etiologic diagnosis of hepatitis B viral disease.