Intraperitoneal Injection of Ginseng Extract Enhances Both Immunoglobulin and Cytokine Production in Mice

Ginseng is one of the most widely used Chinese herbal medicines. In this report, the relatively short-term effect of ginseng extract on the immunoglobulin production and cytokine production was studied. The ginseng extract was prepared by boiling the ground ginseng root in 50% ethanol. The specific pathogen-free mice were intraperitoneally (i.p.) injected with various doses of ginseng extract for 3 consecutive days. The results indicated that the serum levels of immunoglobulin (Ig)M, IgG and IgA were significantly elevated after the mice were i.p. injected with 4 g/kg/day of ginseng extract. Under in vitro condition, the lipopolysaccharide (LPS)-stimulated spleen cells showed a dose-dependent increase in secretion of IgM, IgG and IgA. However, at a higher dosage (4 g/kg/day), the amount of IgA secretion began to decline. The serum level of interleukin (IL)-2, interferon (IFN)-γ [T-helper (Th)1-type cytokines] and IL-4 and IL-10 (Th2-type cytokines) were significantly elevated after the mice were i.p. injected with 2 g/kg/day or higher doses of ginseng extract. The amount of cytokine secretion by concanavalin A (Con A)-stimulated spleen cells was also significantly enhanced after the mice were i.p. injected with 0.4 g/kg/day or higher dose of ginseng extracted. To further confirm the results from enzyme-linked immunosorbent assay (ELISA), the spleen cells were cultured for 36 hours in the presence of 1 μg/ml of Con A. Total mRNA was isolated and assayed for mRNA expression using reverse transcriptase-polymerase chain reaction (RT-PCR). The results revealed that expression of IL-2 and IFN-γ mRNA were dose-dependently enhanced by the ethanol extract of ginseng. The levels of IL-4 and IL-10 mRNA expression were also elevated in the spleen cells of ginseng-treated mice in comparison with that of the control group. In addition, we observed that the concentrations of IgG1, IgG2a and IgG2b in culture supernatants of spleen cells were dose-dependently increased by in vivo treatment of ginseng extract, suggesting that both Th1- and Th2-type cytokines were involved in IgG production. Our observation in this study demonstrated that the Chinese herbal drug ginseng was able to regulate antibody production by augmenting Th1- (IL-2, IFN-γ) and Th2-type (IL-4, IL-10) cytokine production.