The effects of the specific active
cancer immunotherapy utilizing autologous
tumor tissue particles polymerised with ethylchlorformiate, and used in combination with
PPD tuberculin, were studied with respect to the growth of
mastocytoma (P-815 X 2) in DBA/2 mice. As a control material, animals not immunised or immunised only with the nonspecific reticuloendothelial system stimulator,
PPD tuberculin, were used. The frequency of the
tumor metastases in the organs surveyed (lymph nodes, spleen, liver, kidney, lung and thymus) was lowest in mice having received the specific
immunotherapy regimen. Similarly, the signs of
tumor rejection by the host (
tumor-associated fibrous
scar, lymphocyte and plasma cell infiltration, and disappearance of the
tumor tissue totally or subtotally) were found to be most pronounced in this series of mice. The findings were discussed against the background of the successful clinical trials made with this mode of specific
cancer immunotherapy during the recent few years in patients whose
neoplasia had escaped the reach of conventional
cancer therapy. The findings were also discussed in the light of the mechanisms involved in
cancer immunity in general, and a conclusion was drawn that this kind of specific active
cancer immunotherapy seems to exert beneficial effects on the host's immune system, and thus seems to contribute to
tumor rejection by the host.