Tumoricidal activity of mouse peritoneal macrophages treated with Viscum album extract.

Macrophages from mice treated with Viscum album extract were shown to be active in inhibiting the proliferation of tumour cells in culture. These activated macrophages have now been shown to protect mice from dying of progressive tumours when injected intraperitoneally into the animals. Prophylactic as well as multiple treatments with macrophages activated with Viscum album extract seemed more effective than a single treatment. The present finding suggests that in addition to a direct cytotoxic effect of Viscum album extract, the activation of macrophages may contribute to the overall antitumor activity of the drug.