Medicinal mushrooms and cancer chemoprevention While the foregoing antitumour studies on animal models and human clinical trials (Chapters 6 and 7) have used relatively pure extracted polysaccharides it has also been possible to demonstrate antitumour effects when the animal diet has been enriched with either powdered fruit-bodies or liquid concentrates from various edible medicinal mushrooms. Powdered fruit-bodies of Lentinus edodes were supplied orally in the diet (20%) of CDF1 mice who had been inoculated with synergenic IMC carcinoma cells and C3H/He mice inoculated with MM-46 carcinoma cells (Nanba et al., 1987). The MM-46 carcinoma growth was strongly inhibited (79%) whereas the IMC carcinoma growth was much less affected (21% inhibition). A further series of experiments examined macrophage spreading and phagocytosis of latex beads in both normal and tumour-bearing mice fed on a diet supplemented with powdered L. edodes (Nanba and Kuroda, 1987). A decreased spreading rate of macrophage in CDF1 mice but an increase in C3H mice were observed. However, both the spreading rates and phagocytosis of macrophages in tumour-bearing mice of either strain were significantly depressed when compared to non-tumour bearing animals. Cytotoxicity activity of natural killer cells (NK) and/or lymphokine-activated killer cells (LAK) was significantly increased in mice on feed enhanced with powdered L. edodes when compared to mice on normal feed. Pre-treatment of the cells with anti-Thy 12 monoclonal antibodies and complement reduced the cytotoxicity activity by approximately 50% in both mushroom-fed mice and mice on normal feed strongly implying that cytotoxic T cells also participate in the tumour-inhibiting activity of L. edodes.