Effect of Bacillus Calmette-Guérin cell wall skeleton on the induction of the cytotoxic and suppressor T cells against syngeneic tumor in the mouse.

The effect of Bacillus Calmette-Guérin cell wall skeleton (BCG-CWS), which is one of the well-established immunopotentiators, on the induction of either cytotoxic or suppressor T cells against syngeneic tumor S1509a was investigated by an in vitro assay system. BCG-CWS showed an apparent augmenting activity in the induction of cytotoxic T cells against a syngeneic tumor when it was administered subcutaneously into mice with mitomycin C (MMC)-treated tumor cells in a form of oil-in-water emulsion. In addition, cytotoxic T cell activity was dominantly generated in regional lymph nodes. Furthermore, the immunized animals developed stronger resistance against the second inoculum of the same viable tumor cells. However, BCG-CWS had no effect on the induction of suppressor T cells in tumor-bearing host (TBH), and could not induce cytotoxic T cells against the homologous tumor in TBH in which suppressor T cells had been rapidly activated. The growth of tumor was neither suppressor nor enhanced, even if an oil-attached BCG-CWS was administered in TBH.