[Age-dependent anti-tumor activity of lentinan in mice]

During the course of aging, the weight percentage of organs such as kidney to body weight remain almost unchanged, whereas the weight of the thymus decreases significantly. The antitumor activity of Lentinan is constant in mice younger than 1 year (52 weeks). From 52 weeks, aging has a suppressive effect on antitumor activity. Even in aged mice, administration of Lentinan was shown to be effective, and better results were obtained through chronic administration, even with a smaller dose. Lentinan enhanced delayed cutaneous hypersensitivity in aged mice similarly to that in young mice. Thymus homogenate showed synergism with Lentinan in 2-year-old mice for suppression of tumor growth, although thymus homogenate alone showed no effect. These results show that Lentinan is effective as an anticancer immunopotentiator in aged animals in a similar way to young animals.