Enhancement of natural killer cell activity in vitro against human tumor cells by some plants from jordan

The effect of different concentrations (0, 0.01, 0.1, and 0.5 mg/ml) of plant aqueous extracts on the anti-tumor activity of natural killer (NK) cells isolated from human blood was examined. Plant extracts induced significant enhancement of (26.6-67.7%) of NK cell activity against K562 tumor cells. This increase in NK cell cytotoxicity was found to be due to the enhancement of NK cell production of interferon-gamma (87-337%), and on tumor necrosis factor-alpha (60-200%). Furthermore, the release of both granzyme A and N-acetyl-beta-D-glucosaminidase was increased significantly when compared with controls. Activation of granzyme A and N-acetyl-beta-D-glucosaminidase was clearly observed ranging from 24.2-106.4% to 26.8-110.7%, respectively. Lastly, in the absence of IL-2, plant extracts caused a significant increase in NK-cell-induced cytotoxicity (256%) against K562 tumor cells, and in the presence of IL-2 stimulated cells plant extracts caused an increase in NK cell-cytotoxicity (112%).