The effect of mouse interferon gamma (IFNg) on the proliferation of He
pa-1c1c7, mouse hepatoma cells was analyzed by means of [H-3]thymidine
incorporation. IFNg did not suppress the proliferation of Hepa-1c1c7
cells cultivated alone, however, it effectively suppressed in cocultur
e with B6C3F1 mouse hepatocytes and in IFNg-treated mouse hepatocyte-c
onditioned media. Suppression of proliferation of hepatoma cells was d
etected only in the IFNg-treated hepatocyte-conditioned media but not
in the control hepatocyte-conditioned media. The magnitude of suppress
ion depended upon the amount of IFNg used in the preparation of condit
ioned media. The suppressive effect of IFNg-treated hepatocyte-conditi
oned media was retained by an ultrafilteration membrane (M.W. cut off
30,000), and its activity was abrogated by trypsin digestion and heat
treatment. These results suggest that IFNg-treated mouse hepatocytes m
ay release a soluble mediator(s) which suppressed the proliferation of
hepatoma cells and that IFNg interactions with hepatocytes could be i
mportant to the antitumor defense mechanisms of the liver.