The test of non-specific cell-mediated response in animals with transplantable tumours stimulated with calf thymus extract.

Investigations were carried out on the non-specific cell-mediated response in mice with transplantable tumours: LLC in mice C57Bl and F1(C57Bl X C3H), and SAL-l tumour in Balb/c mice. The malignant cells were implanted subcutaneously for observation of changes in the non-specific cell-mediated response at the time of the local growth of the tumour, and injections into the vein or into the foot-pad were made for studying the non-specific cell-mediated response at the time of tumour dissemination. In each series of the experiments the animals received an extract of calf thymus--the preparation TFX-Polfa. The control groups had the tumour cells implanted or injected but were not given TFX. For determining the non-specific cell-mediated response the animals were immunized with picryl chloride. In both experimental models, that is with subcutaneous implantation and with injections intravenously or into the foot-pad a decrease of the non-specific cell-mediated response was observed progressing gradually with extension of the tumours. Long-term administration of TFX in doses of 0.1 mg per mouse prevented the decrease of the non-specific cell-mediated response in the first place in mice with subcutaneous implantations. In mice with malignant cells injected intravenously or into the foot-pad TFX administration had no evident effect on the value of the test. This observation suggests that TFX prevents the development of a secondary immune deficit in mice with subcutaneous transplanted tumours--that is mainly at the time of local growth of the tumour, but is of little use in the phase of tumour dissemination.