North American ginseng (Panax quinquefolium) root extract (NAGE) with known ginsenosides composition was examined for its affinity to stimulate human tumour necrosis factor alpha (TNF-alpha) production in human peripheral blood mononuclear cells. Case studies were conducted in three donors, one that was diagnosed with an atopic allergy and two that were normal, healthy subjects. Cultured mononuclear cells were incubated with varying concentrations of NAGE for up to 72 h and culture media were tested for TNF-alpha concentration. Direct stimulation of mononuclear cell TNF-alpha production in vitro by NAGE occurred as early as 6 h with 200 microg NAGE/mL. The stimulation of TNF-alpha production was confirmed by TNF-alpha mRNA gene expression. These interesting results show the immunostimulating activity of NAGE components in reference to TNF-alpha production. This observation requires further investigation with more subjects to determine the affinity of ginseng in stimulating the human immune system. Moreover, the method of evaluating this response is very useful for standardizing ginseng extracts to a known bioactivity.
