Transplantability and metastasibility of an MCA-induced sarcoma in nude mice. Influence of transfer of thymus cells and adoptive immunity.

Challenge of C57/(nu/nu) mice with an MCA-induced sarcoma, MCG101, induced in C57BL/6J mice, disclosed a higher resistance subcutaneously and intravenously than in syngenic C57/(+/+) mice. Transfer of 5 times 107 thymus cells to the nude mice brought their resistance to subcutaneously injected tumour cells back to the level of the C57/(+/+) mice, but only with the highest tumour cell doses tested, i.e. 5 times 104 and 105 cells. Against intravenously injected tumour cells a similar effect by the thymus cells was only suggested. Spontaneous metastases from the same tumour transplanted to the tail did occur in the nude mice and were possibly facilitated by specifically sensitized spleen cells. The results indicate that the resistance to subcutaneously injected tumour cells in nude mice may well be dependent on their incapability to develop thymus-dependent immuno-responses and that spontaneous metastases can be facilitated by a weak immuno-response.