The effects of the specific active
cancer immunotherapy utilizing autologous
tumor tissue particles polymerise with ethylchlorformiate, and used in combination with
PPD tuberculin, were studied on the growth of
chloroma in an inbred strain of Wistar rats. As control animals, rats not immunised, or immunised with autologous muscle tissue
polymer +
PPD, or
PPD alone, were studied. A clear-cut enhancement of
tumor growth was observed in the group of animals receiving the
tumor polymer, as evidenced by the largest
tumors, the lowest incidence of
tumor rejection and the lack of histological signs of host response against the growing
chloroma. Immunisation with the
PPD tuberculin, on the other hand, favorably influenced the host's immune system thus contributing to the
tumor rejection and the development of pronounced host response in a high percentage of cases. The results were discussed in the light of favorable experiences gained with this mode of
cancer immunotherapy in a number of clinical trials, as well as in a previous experimental DBA/2 mouse
mastocytoma model. This apparent controversy between the previously obtained and the present results was interpreted to be caused by the different antigenic properties of the
tumors used in these studies. The importance of the selection of an appropriate model system was emphasized, when it was attempted to obtain data relevant to human
tumors for experimental
cancer immunotherapy systems.