Response of syngeneic murine lymphomata to immunotherapy in relation to the antigenicity of the tumour.

The responses of four murine lymphomata, transplanted in their syngeneic hosts and differing widely in their biological properties such as tendency to metastasize and "strength" of tumour specific antigen, to immunotherapy, were investigated. Following the injection of a known number of tumour cells, the mice were treated either by administration of irradiated tumour cells, living BCG or both. In general, the response to BCG alone was small even in the most responsive tumours, irradiated cells were more effective and the best results were obtained by a combination of the two procedures. "Cures" were only obtained with the most antigenic of the tumours tested and then only when the live tumour cells were inoculated intraperitoneally. The effect of these treatments on the rate of growth of tumour when the cells were given subcutaneously was small but the rate at which metastatic spread occurred from the s.c. site was slowed and for one of these tumours this was quite marked.