Prophylactic anti-tumor effect of Hochu-ekki-to (TJ41) by enhancing natural killer cell activity.

We assessed the anti-tumor activity in vivo of a kampo (Chinese) prescription Hocku-ekki-to (TJ41) in the rat and mouse tumor model. The growth of tumors was clearly inhibited in syngeneic animals given TJ-41 prophylactically. The splenic NK cells of TJ-41-treated WKA rats showed enhanced cytotoxicity against tumors including NK-sensitive YAC-1 targets. TJ-41 did not increase the splenic NK cell population, but it appeared that TJ-41 could potentiate the cytotoxic capability of each NK cell. These data indicate that TJ-41 may be useful for prophylactic immunotherapy of cancer. One of the mechanisms of the potent inhibitory effect by TJ-41 on tumor growth might be explained by its enhancement of NK activity.