It was reported that flavonoids significantly enhanced lymphocyte proliferation and caused a significant recovery of IL-2 production in mice inhibited with hydrocortisone acetate (Liang et al.,1997) .Therefore , the increase in lymphocyte proliferation , NK cell function and the release of IL-2 from normal PBMC in our study may be due to the effect of isoflavones , compounds of the flavonoid group , found in the extract of D. scandens. Our finding may explain that the augmentation of NK cell function could possibly result in the release of IL-2 with a consequent enhancing of lymphocyte proliferation In addition , the extract-induced proliferative response may continuously induce the secretion of IL-2