The effect of anti-malarial drugs on human natural killer cells in vitro

Human natural killer (NK) cell cytotoxicity against K-562 target was found to be markedly depressed by quinacrine, mefloquine, pyrimethamine and chloroquine. The most potent were quinacrine and mefloquine. Two other drugs tested, quinine and primaquine, displayed no significant effects even after long incubation periods with effector cells. The results showed that the inhibitory effects were not related to an inhibition of effector cell binding to target or to a toxic effect on NK cells.