Immunomodulatory effects of the methanolic extract of Epimedium alpinum in vitro

The effect of the methanolic extract of root and rhizome of Epimedium alpinum (MEEA) on phenotype and functions of rat lymphocytes in vitro was studied. It has been found that MEEA at lower concentrations (0.1 mu g/ml and 1 mu g/ml) significantly enhanced proliferation of splenocytes and thymocytes triggered by concanavalin A (Con A), whereas higher concentrations of the extract (50 mu g/ ml-500 mu g/ml) were inhibitory. The stimulatory effect of MEEA on Con A-induced proliferation of splenocytes correlated with the up-regulation of interleukin-2 receptor alpha (IL-2R alpha) expression. In addition, increased production of IL-2 was observed when a blocking IL-2R alpha monoclonal antibody (mAb) was added to cell cultures. MEEA-suppressed proliferation of splenocytes was due to the inhibition of IL-2 production, the down-regulation of IL-2Ra expression and the induction of apoptosis. Cellular proliferation in the presence of inhibitory concentrations of MEEA higher than 50 mu g/ml could not be restored by the addition of exogenous IL-2. (c) 2006 Elsevier B.V. All rights reserved.