IMMUNITY AS THE PREDOMINANT FACTOR DETERMINING METASTASIS BY MURINE LYMPHOMAS

Metastatic behavior of the L5178E (non-M) lymphoma and a highly metastatic subline L51787ES (M) were studied in syngeneic DBA2 mice. The non-M tumor rarely metastasized in intact syngeneic mice, but produced extensive and rapidly lethal metastases when implanted into irradiated recipients. Metastatic behavior of the M subline was unaffected by irradiation of the host. By conventional transplantation criteria, the non-M tumor was more immunogenic than the M subline. Both tumors, produced similar responses in a lymph node weight-gain assay. Host-cell infiltration of tumors growing s.c. was much greater in the non-M than the M, the infiltrating cells being Fc-receptor-positive and maturing into macrophages after 2 days in vitro. Although spontaneous in vitro motility of the M cells was much greater than that of the non-M, metastatic behavior of the tumors is clearly determined by host immunological responses.