DIFFERENCES OF HOST IMMUNE RESPONSE AND OF SENSITIVITY TO CHEMOTHERAPEUTIC AGENTS BETWEEN TWO CLONES OF RAT FIBROSARCOMA WITH DIFFERENT METASTATIC POTENTIAL

Abstract

Differences of host immune response and of chemosensitivity between two clones derived from a methylcholanthrene-induced rat fibrosarcoma and exhibiting different tumorigenic and metastatic potentials were examined. Clone G, which has no metastatic potential, was more sensitive to natural killer cytotoxicity by syngeneic rat spleen cells than clone A, which is highly metastatic. The colony formation of clone G was strongly inhibited by the supernatant obtained from coculture of lymphocytes with either of these two clones. In contrast, the colony formation of clone A was not inhibited by these supernatants. Inhibition of the colony formation of clone G was dependent on the dilution of the supernatant and the incubation time of the lymphocytes and tumor cells used to generate the supernatant. The supernatant from cocultures of lymphocytes and clone G inhibited the colony formation of clone G more strongly than the supernatant from cocultures of lymphocytes and clone A. There was no difference between these two clones in chemosensitivity to seven of the ten chemotherapeutic drugs tested.