Inhibition of tumoral graft growth by pretreatment with normal or heat-modified tumoral cells

Abstract

The intravenous injection of Ehrlich tumour cells (TC) into Swiss mice, or BP8-fibrosarcoma cells into C3H mice, caused no intra-organ dissemination of the tumour but resulted in increasing resistance of animals to these two tumours. The percentage of mice protected against a regularly lethal dose of TC given intraperitoneally (i. p.) increased with the dose and the number of immunizing injections to the i. p. challenge. However, after high or repeated doses a cancerous nodule sometimes developed at the site of intravenous injections (penis vein), which caused death of the animal, not by extension of the tumour but by urethral occlusion. Moderate heating (46, 49,5 or 52°C) of the TC did not impair their immunogenicity but prevented their multiplication in normal mice. It was thus possible, by intradermal injections of heated TC, to protect mice against a dose of intact TC. The efficiency of prophylaxis depended on the temperature to which the cells were exposed (optimal temperature depending on the type of tumour), on the number of injections and on the medium in which the cells were suspended. When Freund's complete adjuvant was used, all mice were protected against tumour ascites following challenge.