Effects of chlorinated solvents on the natural lymphocytotoxic activities of human liver immune cells.

Inhibition of the natural immune system may be involved in the liver cancer caused by some non-genotoxic chemicals when they are administered at high doses to certain strains of animals. Previous studies have shown that some chlorinated solvents inhibit liver natural immune function in rodents. In this preliminary study, the effects of in vitro exposure to three commonly used chlorinated solvents were determined on three tumoricidal activities expressed by isolated human liver immune cells-natural killer (NK), natural cytotoxic (NC) and natural P815 killer (NPK) (Wright and Stacey, 1991) cell activities. The NK, NC and NPK cell activities of immune cells isolated from three human livers were 115, 45 and 53 lytic units (LU(20%)/10(6) effector cells), respectively. In vitro exposure to trichloroethylene (TRI) inhibited all three natural immune activities, and the ranking of sensitivity was NPK NC NK. Tetrachloroethylene (TET) inhibited NC and NPK cell activities, but had little effect on NK cell activity. 1,1,1-Trichloroethane (TCE) had little or no effect on the three tumoricidal activities examined. Overall, these data show clear similarities to the results obtained in vitro using cells from experimental animals.