Intraperitoneal injection of ginseng extract enhances both immunoglobulin and cytokine production in mice

Abstract

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)-gamma[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 microgram/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-gamma 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-gamma) and Th2-type (IL-4, IL-10) cytokine production.