The use of polymerised autologous tumor tissue particles for experimental cancer immunotherapy in rats bearing Shay chloroma.

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.