Hepatitis-associated antigen in immunofluorescence I. Interfering factors

Synopsis By means of the indirect immunofluorescence test, Australia hepatitis-associated antigen (Au/SH) was studied in human liver cell suspensions obtained by needle biopsy. Fluorescence staining was performed with human anti-Au/SH immunoglobulins; controls with non-immune human and guinea-pig sera and with cellular substrates lacking Au/SH antigen (rat regenerating liver) were also carried out.Eight out of forty-one unselected patients showed specific fluorescence in their liver cells without any correlation with clinical diagnosis, presence of Au/SH antigen in the serum or of virus-like particles in the hepatocytes by ultrastructural examination. The positive cases were characterized by intranuclear fluorescent granules in, probably, nucleoli; this was confirmed by cytochemical investigations. However, the eight cases positive to anti-Au/SH antiserum showed a quite identical nucleolar fluorescence with non-immune human and guinea-pig sera. In addition, histochemical and ultrastructural examinations demonstrated, only in these positive cases, an increased nucleolar RNS-synthesis.The same results were obtained with cell suspensions of rat regenerating livers removed 20–24 hr after partial hepatectomy. These data strongly support that enhanced nucleolar RNA synthesis is responsible for non-specific positive fluorescence.Elution and digestion tests demonstrated that a heat-labile C'lq-like factor can interfere in the positivity of this fluorescence test.