Investigations of liver biopsies for Australia antigen by immunofluorescent technique.
134 liver biopsies obtained from 124 patients with various diseases of the liver were examined by the direct immunofluorescent technique for the Australia antigen. FITC-labelled IgG fractions prepared from three different sera containing antibody to the Australia antigen were used. Controls included FITC-labelled IgG fractions of sera containing antibodies against human immunoglobulins, complement factors and herpes simplex virus. 
 
The three antibodies to the Australia antigen employed showed identical fluorescent patterns and reacted with the same biopsies. In 68 biopsies prepared and examined within 12 hr, speckled or granular fluorescence was noted in the nuclei of the hepatocytes in all cases irrespective of the clinical or histological diagnosis or the serological reaction for the Australia antigen. The antigen in the nuclei of the hepatocytes proved to be very labile. 
 
It is concluded that IgG prepared from sera containing antibodies to the Australia antigen may have two antigenic specificities, one precipitating with the Australia antigen in serum and another reacting by immunofluorescence with a labile antigen which appears to be a constituent of normal liver cell nuclei.