Potentiation of natural killer cell activity with myricetin.

BACKGROUND/AIM Myricetin is a flavanoid that can be found in a variety of food sources, including red wine. Several reports have indicated that flavonoids may reduce the disease risk of cancer. The aim of the present study was to investigate the effect of some flavonols on natural killer (NK) cell activity. MATERIALS AND METHODS A time-resolved fluorometric assay (TDA-labeled K562 target cells) was used for measuring the cytotoxic activity of NK-cells pre-treated with different flavonoids. RESULTS A limited number of flavanoids was tested for their ability to enhance the NK activity. Pre-treating NK cells with myricetin, could potentiate their ability to kill K562 erythroleukemia cells. This enhancement of the NK activity was observed in a dose-dependent manner. Similar treatments with the structurally similar molecule quercetin, that lacks one hydroxyl group, did not have any impact at all on NK activity. CONCLUSION The enhanced cytotoxic activity observed with myricetin-pretreated-NK cells might shed some light on human studies indicating a preventive role of flavonols against cancer.