Enhancing effect by metabolic inhibitors on the killing of tumor cells by antibody and complement.

Two chemically induced, antigenically distinct guinea pig hepatoma cell lines, line 1 and line 10, which are resistant to killing by rabbit anti-Forssman or specific antitumor antibody and complement, can be rendered susceptible when the cells are pretreated with metabolic inhibitors and drugs commonly used for the treatment of cancer patients. The effect appears within 7 hr after initial contact with the inhibitors and is dependent on temperature and on inhibitor concentration; the effect is reversible within 7 hr, and the process of reversion is also temperature dependent. Not all preparations of tumor cells were rendered susceptible following treatment with inhibitors. In some cases, susceptibility to killing by complement was observed with anti-Forssman antibody but not antitumor antibody. No clear correlation between known metabolic inhibitory activity of the inhibitors and conversion to the sensitive state could be made. The results suggest that properties of nucleated cells, which are under metabolic control, play an important role in the killing efficiency of antibody and complement.