[New direction in immunochemotherapy of cancer]

For the most effective cancer immunochemotherapy, the suppression of suppressive factors is very important as well as the activation of cytotoxic effector cells. We studied suppression of suppressor T cells with cancer chemotherapeutics at a usual dosage. One of our project teams showed that a single administration of bleomycin at 5 mg/kg to WKA rats vaccinated with irradiated syngeneic KMT-17 tumor cells before or after the vaccination strongly augmented the effect of the vaccination to give a good curability and ILS in the KMT-17 bearing rats, and that this effect of bleomycin resulted from suppression of suppressor cells. Another team of ours demonstrated a marked curable effect of combination therapy with cyclophosphamide and forphenicinol, a small molecular BRM, on syngeneic mammary adenocarcinoma in C3H/HeN mice producing a strong specific antitumor immunity after the cure. The third team showed that oxanosine, a new antitumor antibiotic, bore not only a direct tumoricidal activity but suppressor-suppressing and macrophage-activating activities. The fourth team studied cytoelectrophoresis of suppressor T cells and showed that immuno-specific suppressor T cells moved more slowly than non-stimulated normal T cells, the peak coming between the peaks of normal T cells (high mobility) and B cells (low mobility). This finding is useful for development of a new assay method for Ts-suppressing drugs. This group also studied a new screening method for inhibitors of non-specific suppressor T cells. There are several other approaches to cancer immunochemotherapy, which will be presented at other opportunities.