Inhibition of target cell mitosis as a measure of the cytostatic effects of activated macrophages on tumor target cells.

Studies were carried out in vitro that showed that activated macrophages inhibited tumor target cells from undergoing mitosis. With the use of target cells synchronized in the mitosis phase of the cell cycle, this manifestation of macrophage-mediated cytostatic effects was preceded by the complete inhibition of target cell DNA synthesis as measured by incorporation of [3H]thymidine.