Characterization of the in vitro effect of triethylphosphine gold (auranofin) on human NK cell activity

Pharmacological concentrations of auranofin (oral gold) modulated NK cell activity in a dose dependent biphasic manner. In vitro low doses enhanced NK cell activity, while high doses inhibited the NK cell activity. Sodium aurothiomalate (parenteral gold) had no effect. The effect of auranofin on NK cell function was irreversible and independent of the presence of monocytes. Neither IF nor Il-2 abolished the auranofin-suppressed NK cell activity. When NK cell activity was enhanced by low doses of auranofin, both IF and Il-2 could further boost the NK cell function. Using percoll fractionated NK cell enriched populations in a single cell agarose assays, it was shown that auranofin did not influence effector/target cell conjugate formation. The effect of auranofin on NK cell activity is thus due to an influence on the lytic step.