EFFECTS OF DIHEPTYLDISELENIDE (DDS) ON HUMAN TUMOR-CELL LINES AND ON PERIPHERAL-BLOOD MONONUCLEAR-CELLS

In vitro effects of graded concentrations of diheptyldiselenide (DDS) on human tumor cell proliferation, and on the poliferative responses a nd immunological functions of peripheral blood mononuclear cells (MNC) were investigated. The agent significantly decreased tumor cell proli feration in a dose and time dependent manner. Proliferative responses of MNC to phytohemagglutinin (PHA) and interleukin-2 (IL-2) were also significantly depressed when MNCs were exposed to DDS at the onset of the culture. Pretreatment of MNCs with DDS (250 mu M for 18 h) led to a significant increase in NK activity only in MNC samples showing very limited baseline NK function. On the other hand, generation of LAK ce lls was significantly inhibited by DDS. However, when the agent was ad ded to the effector and target cell mixture during the 4 h Cr-51 relea se cytotoxicity assay, no influence was found on NK and LAK-mediated t arget cell lysis. These studies show that high concentrations of DDS i nhibit tumor cell proliferation and could also impair certain prolifer ative-dependent immune functions, without directly affecting cell-medi ated cytolytic activity of effector cells.