[Augmentation of resistance against metastatic tumor cells after local administration of PSK]

Local administration of PSK augmented the generation of cytotoxic lymphocytes and the induction of resistance against metastatic tumor. Augmented generation of cytotoxic lymphocytes may be ascribed to local effects of PSK in the lymph nodes, since this is mediated by Lyt-1+2+ cells. Local administration of PSK increased the threshold number of metastatic tumors eliminated by hosts. This finding seems to be important in relation to augmentation of resistance against metastasis or local implantation with a limited number of tumor cells.