Evaluation of the stimulatory effect of Epimedium alpinum L. methanolic extract on the immune response in vivo.

The effect of the methanolic extract of the underground parts of Epimedium alpinum L. (MEEA) on the immune response to Keyhole Limpet Hemocyanine (KLH) or alloantigens in vivo was studied in AO rats. Immunization of experimental animals with KLH or allogeneic lymphocytes together with MEEA was followed by an increase in cellularity of draining lymph nodes (LN) and enhanced proliferation of LN lymphocytes after their restimulation with specific antigens in vitro, compared to control rats immunized without MEEA. These effects correlated with an increase in relative values of B, MHC class II+, CD25+ and CD71+ cells, whereas percentages of T cells and both subsets of T cells (CD4+ and CD8+) were not significantly altered. As a consequence of higher LN cellularity, total numbers of all cell subsets in the MEEA-treated group of rats were significantly increased, compared to the corresponding control. The addition of MEEA together with KLH in vitro to LN lymphocytes of rats immunized with KLH or KLH and MEEA in vivo was manifested by significant increase (0.1 microg/ml of MEEA) and decrease (50 microg/ml and 100 microg/ml of MEEA) of cell proliferation, respectively. However, when LN lymphocytes from rats, immunized in vivo with KLH and MEEA, were stimulated in vitro with MEEA together with an anti-alphabeta T cell receptor monoclonal antibody (R73), their proliferation was siginificantly inhibited. Taken together, obtained results suggest that MEEA possesses immunostimulatory activity in vivo, but some components from the extract exert immunosuppressive effects in vitro on previously in vivo activated T cells.