Abstract: Using methods of fluotescence flow cytometry and Western blot analysis,Rg₁ wasfound to enhance the expression of IL-2 receptor α chain and inhibit the release of soluble IL-2receptor.In in vitro experiment,Rg₁ showed no influence on Con A-induced increase of cytoplasmicfree calcium concentration,but significantly increased the levels of intracellular cAMP and cGMP inaged animals.In view of the im portant role of cAMP and cGMP as second messengers in theregulation of immune system , the results of the present studies suggest that one of the mechanisms bywhich Rg₁ enhances immune function in old rats might be mediated by increase of cAMP and cGMPcontents,resulting in IL-2 gene expression and splenocyte proliferation.