Augmentation of natural killer cell activity in vivo against tumour cells by some wild plants from Jordan.

Twelve aqueous extracts prepared from Jordanian plants that are currently used in traditional medicine to treat various types of cancer were tested in mice for their augmentation of natural killer cells in vivo in generating cytotoxicity against YAC tumour targets. After 1 week of oral administration of aqueous extracts of fresh Nigella sativum (N.s.) seeds and Allium sativum (A.s.) bulbs significant augmentation of splenic natural killer (NK) cells (62.3% +/- 6.4% and 52.6% +/-5.4% cytotoxicity, respectively), was obtained in comparison with spontaneous activity (24.5% +/- 1.6%) at 200:1 effector:target ratio. Onopordum acanthium (O.a.) stem and leaves and Allium cepa (A.c.) bulbs showed intermediate augmentation (38.6% +/- 3.8% and 30.6% +/- 3.4% cytotoxicity, respectively) while the rest showed insignificant augmentation activity. The fresh aqueous extract of a mixture of the plants with high and intermediate activity showed little insignificant augmentation activity (72.7% +/- 6.7% cytotoxicity) of NK cells compared with that obtained with each plant alone.