Interference of the induction of suppressor cells by a streptococcal preparation, OK-432 through the blocking of suppressor inducer T-cells

The effect of OK-432 on suppressor inducer T cells in the generation of suppressor cells was investigated to determine its mechanism of action as an immunopotentiating agent. Suppressor cell activities induced by sera from patients with advanced cancer (stage III, IV or recurrence) were found to be as high as those induced by Con-A. Suppressor activity induced by Con-A or serum from cancer patients resided in CD8 + T cells, although CD4 + T-cells were required for the induction of suppressor cells. Significant increases in the CD4 +2H4 + T cell population after stimulation with either Con-A or sera from the advanced cancer patients were observed when compared with stimulation by normal serum. Stimulation with Con-A induced suppressor cells as well as a significant increase of CD4 +2H4 + T-cells. The presence of OK-432 during the generation of suppressor cells, however, significantly reduced the suppressor activity and apparently blocked the increase of CD4 +2H4 + T-cells. Thus, it is suggested that OK-432 may interfere with the induction of suppressor cells through the blocking of CD4 +2H4 + suppressor inducer T-cells.