Suppressive effects of Ganoderma lucidum on proliferation of peripheral blood mononuclear cells.

The basidiocarps of Ganoderma lucidum have been used for prevention and treatment of various diseases in the Orient. Methanolic extracts of this mushroom were applied to human peripheral blood mononuclear cell (PBMC) culture systems in the presence of various immunostimulating or immunosuppressive agents. Phytohemagglutinin-induced cell proliferation was reduced to 14% of that of the control by a GLE fraction that is the neutral component of the methanolic extracts of the carpophores. 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced cell proliferation was inhibited by the fractions of GLA, GLC, GLE and GLG. However none of these fractions inhibited proliferation of the PBMCs stimulated with TPA plus ionomycin (IM). Treatment of the PBMCs with cyclosporin A (CsA) led to blockage of the cell proliferation to 9% of that of the control. When the cells were cultured with the methanolic fractions in the presence of CsA, concentration dependent inhibition of the cell proliferation was observed by the addition of GLE and GLG fractions. On the contrary, the GLH fraction recovered the CsA induced inhibition of the cell proliferation. Taken together, among the methanolic fractions, GLE showed the highest inhibitory activity. This fraction might inhibit the protein kinase C signal pathway and accelerate the CsA signal pathway.