PERITONEAL EXUDATE MONONUCLEAR PHAGOCYTE COLONY‐FORMING CELLS: THEIR PROLIFERATIVE STATE IN VIVO AND SENSITIVITY TO CYTOTOXIC AGENTS

We investigated the proliferative state of peritoneal exudate macrophage colony‐forming cells (PE‐CFC) by exposing them to [³H]thymidine with a high specific activity in vitro and by administering cytosine arabinoside and methotrexate in vivo. Since [³H]TdR had no appreciable killing effect on PE‐CFC and since the drug treatment caused no reduction in the appearance of PE‐CFC, we concluded that the majority of PE‐CFC, if not all, are not in active cell cycle. The production of PE‐CFC was, however, suppressed by the administration of nitrogen mustard, cyclophosphamide, BCNU and vinblastine.