Effect of cisplatin treatment of human monocyte cell line U937 on the induction of tumoricidal activity.

U937, a human monocyte-like, cell line was checked for cytotoxic activity against tumor target cells. Untreated U937 cells showed little cytotoxicity against tumor cells. Granulocyte-macrophage colony stimulating factor (GM-CSF) and LPS significantly activated the U937 cells to tumoricidal state. Treatment of U937 cells with cisplatin did not enhance the tumoricidal activity. Similarly, interferon gamma (IFN-Y) and macrophage colony stimulating factor (M-CSF) could also not activate either the tumoricidal activity of U937 cells. Pretreatment of U937 cells with GM-CSF for 24 h and then the treatment with cisplatin significantly augmented the tumoricidal activity as compared to that of GM-CSF alone.