The changing pattern of the splenic lymphocyte subsets in tumor-bearing mice after oral treatment with OK-432.

The aim of this study was to investigate the influence of oral administration of OK-432 on the tumor growth of tumor-bearing mice. In addition, the changing pattern of the splenic lymphocyte subsets of tumor-bearing mice was evaluated by flow cytometry. OK-432 at a dose of 0.1, 1 or 10 KE was administered orally every 3 days or every other day for 30 days to subcutaneously Meth A tumor-inoculated mice. The tumor growth was significantly inhibited in the 1 KE every 3 days group, in the 1 KE every other day group and in the 10 KE every 3 days group. In the 10 KE every other day group, OK-432 inhibited the tumor growth on days 10 and 20, while the agent did not show a marked inhibitory effect on day 30. The percentages of splenic L3T4-positive cells and splenic asialo GM1-positive cells were significantly increased in the 1 KE every other day group, while the Lyt2+/Thy1.2+ ratio was decreased. On the other hand, in the 10 KE every other day group, OK-432 showed no effect on the percentages of splenic L3T4-positive cells and Lyt2+/Thy1.2+ ratio on days 20 and 30. Our results suggest that the antitumor effect of oral administration of OK-432 may be correlated with the changing pattern of L3T4-positive cells and Lyt2+/Thy1.2+ ratio.