Mechanisms by which activated normal macrophages destroy syngeneic rat tumour cells in vitro. Cytokinetics, non-involvement of T lymphocytes, and effect of metabolic inhibitors.

Abstract

Analysis of the kinetics of the in vitro interaction between nonimmune activated macrophages and syngeneic tumour cells (induced in inbred DA rats by polyoma virus, dimethylbenzanthracene or methylcholanthrene) has shown that a distinctive series of events can be clearly separated. The earliest consequence of interaction detectable by objective means is a marked decrease in tumour cell proliferation as reflected in the reduction of the capacity of tumour cells to incorporate DNA precursors such as [3H]thymidine. By 3—4 hours, the cytostatic effect is strongly marked, and is essentially established after 12 hours of interaction. Shrinkage, agglutination and decrease in the number of tumour cells as examples of the morphological consequences of cytostatic target cell damage accomplished by activated macrophages are rarely perceptible before 10–12 hours although the tumour cells have completely disappeared after 24–48 hours.