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 L(3)T(4)‐positive cells and splenic asialo GM(1)‐positive cells were significantly increased in the 1 KE every other day group, while the Lyt2(+)/ Thyl.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 L(3)T(4)‐positive cells and Lyt2(+)/Thyl.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 L(3)T(4)‐positive cells and Lyt2(+)/Thyl.2(+)ratio.