Ginsenosides from Panax ginseng differentially regulate lymphocyte proliferation

We have examined the immunosuppressive effects of representative ginsenosides (Rb(1), Rb(2), Re and Rg(1)) from Panax ginseng C. A. Meyer on CD4+ and CD8+ lymphocyte proliferation. Ginsenosides differentially modulated lymphocyte proliferation induced by concanavalin A (Con A), lipopolysaccharide (LPS), phytohema-glutinin (PHA) and interleukin-2 (IL-2). Thus, Rb(1) and Re significantly enhanced Con A-induced lymphocyte proliferation, whereas Rg(1) did not affect the proliferation. Interestingly, however, Rb(2) strongly blocked Con A, LPS and PHA-induced lymphocyte proliferation with the IC(50) values of 21.8, 29.0 and 24.0 muM, respectively. Moreover, Rb(2) inhibited Con A-stimulated IL-2 production with an IC(50) of 13.3 muM. In the IL-2-stimulated CD8+ T cell (CTLL-2) proliferation assay, Re and Rg(1) showed strong suppressive effects with IC(50) values of 57.5 and 64.7 muM, respectively. In contrast, neither Rb(1) nor Rb(2) did inhibit CTLL-2 cell proliferation at tested concentrations. These results suggest that ginsenosides from P. ginseng may modulate lymphocyte proliferation in a different manner.