In vitro activation of murine Kupffer cells by lymphokines or endotoxins to lyse syngeneic tumor cells.

Murine Kupffer cells (RC) were isolated in sufficient number and purity to allow in vitro investigations of their tumoricidal capabilities. The identity of the adherent cells as KCs was established by morphologic, histochemical, and functional criteria. The yield of KCs varied from young (high) to old (low) mice but was not affected by the mouse strain. KCs activated in vitro by either endotoxins (lipopolysaccharide) or lymphokines were rendered highly cytotoxic against syngeneic melanoma or fibrosarcoma target cells. These studies indicate that KCs may indeed play a role in destruction of tumor cells in vivo and thus be important in host defense against developing hepatic cancer metastases.