Immunosuppressive properties of a factor isolated from adult rat liver

We have isolated from normal and regenerating rat liver a protein fraction 80,000 molecular weight which inhibits the multiplication of LF hepatoma cells in culture and decreased the 3H-thymidine incorporation into liver DNA in two thirds hepatectomized rats. In the present work, we have shown that this factor possess some immunosuppressive properties. It inhibits the blastogenic response to mitogens for both splenic and thymic cells, in vitro as well as in vivo; the synthesis of SRBC-antibodies is also impaired. Thus this factor which acts upon liver homeostasis seems to play a role as modulator of the immune response.