A morphological analysis of an in vitro model of cytotoxic antitumor activity.

Models of adoptive immunotherapy and cytotoxicity of lymphocytes isolated from tumor tissues were studied. A microcytotoxicity model utilizing serum-free culture conditions was evaluated by light microscopy, scanning electron microscopy, and transmission electron microscopy for antitumor activity. By examining morphologically the relationship between peripheral blood mononuclear cells and tumor-infiltrating lymphocytes, it was demonstrated that the latter and macrophages had morphological features similar to the cytotoxic cells obtained in vitro from peripheral blood. When allowed sufficient time in our culture conditions, the tumor-infiltrating cytotoxic cells seem to kill the tumor cells within a few days to many months. The ultrastructural morphology of the interaction between the cytotoxic cells and the tumor cells was described as well as some proteinaceous secretory granules that seem to be transferred to the tumor cells through these interactions.