Enhancement of spontaneous and lymphokine activated human macrophage cytotoxicity by hyperthermia

Human macrophages grown on hydrophobic teflon membranes from blood-born monocytes were incubated at hyperthermic temperatures for various time periods and then tested for their ability to inhibit the growth of an allogeneic lymphoma cell line (U 937). Incubation at 40.5 degrees C greatly enhanced macrophage cytotoxicity. This effect of hyperthermia developed slowly with an optimal incubation period of 48 h. In addition, lymphokine activation of macrophages for cytotoxicity appeared to be more effective at elevated temperatures.