Ginseng total saponin enhances the phagocytic capacity of canine peripheral blood phagocytes in vitro

The clinical and pharmacological activities of ginseng are known to modulate immune function, metabolic processes and neuro-endocrine system activities. Ginseng saponins are the principle active ingredients in the formation of immune stimulating complexes. The objective of this study was to evaluate the in vitro effect of ginseng total saponin (GTS) on the phagocytic capacity of canine peripheral blood phagocytes. GTS itself did not cause any direct effect on the phagocytic capacity of peripheral blood mononuclear cells (PBMC) and polymorphonuclear cells (PMN) but not peripheral blood monocytes. However, the phagocytic capacity of PMN and monocytes, but not PBMC, was enhanced by the culture supernatant from PBMC treated with GTS. The phagocytic capacity of PMN and monocytes was also increased by treatment with recombinant canine (rc) tumor necrosis factor (TNF)-alpha. The ability of the culture supernatant from GTS-treated PBMC to stimulate the phagocytic capacity of phagocytes was inhibited by addition of anti-rc TNF-alpha polyclonal antibody (pAb) prior to the culture. The amount of TNF-alpha in the culture supernatant from PBMC was shown to increase upon treatment of GTS as compared with that of vehicle-treated PBMC culture supernatant. These results suggest that GTS has an immunoenhancing effect on the phagocytic capacity of canine peripheral blood phagocytes, which is mainly mediated by TNF-alpha released from GTS-stimulated PBMC.