Effects of elm bark (Ulmus davidiana var. japonica) extracts on the modulation of immunocompetence in mice.

The immunomodulative effects of elm bark extract were studied in vitro by the proliferation of splenocytes and the production capacity of three kinds of cytokines [interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha] by mouse peritoneal macrophages cultured with various fractions (methanol, hexane, chloroform, ethyl acetate, butanol, and water) of elm bark extract. Splenocyte proliferation and cell viability of peritoneal macrophages were increased with concentrations of polar fractions, such as butanol and water, in the range of 1-500 microg/mL. Significantly higher levels of the production of all three cytokines were detected with supplementation of methanol extract compared with other fractions. In order to elucidate its effect in vivo, elm bark water extract was orally administrated every other day for 2 weeks. Proliferation of splenocytes and the production capacity of cytokines (IL-1beta, IL-6, and TNF-alpha) by mouse peritoneal macrophages were used as indices for immune activity. Splenocyte proliferation induced by elm bark with lipopolysaccharide or concanavalin A stimulation was enhanced at 500 mg/kg of body weight concentrations compared to that of the control group. In the case of cytokines, the highest production of IL-6 and TNF was detected at 500 mg/kg of body weight concentrations. In conclusion, this study suggests through in vitro and in vivo experiments that Ulmus davidiana var. japonica (elm bark) extracts may enhance the immunocompetent properties such as splenocyte proliferation and cytokine production capacity by activated macrophages and have a protective effect in mice.