Development of concomitant immunity in mice bearing the weakly immunogenic line 1 lung carcinoma.

The interaction between line 1 carcinomas growing s.c. and their spontaneous (or artificial) metastases has been studied in syngeneic BALB/c mice. In contrast to typical murine tumor systems, concomitant immunity, or the ability of primary tumors to suppress the growth of metastases, develops very slowly in this system, such that the metastases that are shed within the first week of tumor growth survive and ultimately prove lethal to the host. The rate of development of concomitant immunity can be accelerated by increasing the hosts' tumor burden or decelerated by exposure of the hosts to X-rays prior to tumor transplant. This cancer system offers, therefore, an excellent model for the therapy of metastases that cannot be obtained with typical murine tumors.