Active Immunotherapy of AKR Mouse Spontaneous Leukemia

Abstract

Active immunotherapy (AI), which is the immune stimulation applied after the establishment of the tumor, has been shown by our first experiments conducted on L 1210 grafted leukemia, to be able to eradicate the neoplastic cell population and to cure the animals However, the leukemic cell population must not exceed 10⁵ [7] and this is a limiting factor. These experiments also showed that the most active modality of immune stimulation for immunotherapy is the combination of irradiated tumor cells and of agents we have called “systemic adjuvants of immunity”, because they potentiate the effect of the specific stimulation produced by these cells, even when applied at different sites and at different times [7, 12]. The most active of these agents is BCG, as shown by a systematic study with a battery of screening tests [11]. BCG given alone, though active in immunoprophylaxis, i.e. when administered before the establishment of the tumor, is usually inactive for therapy [12].