Bioactive proteins represent an important group of functional agents in medicinal mushrooms.Trametes versicolor(L.) Lloyd is a mushroom frequently used in traditional Chinese medicine for its anti-tumor and immunomodulatory activities.A new immunomodulatory protein from T.versicolor,named TVC,was purified by ammonium sulfate precipitation,ion-exchange chromatography and gel filtration chromatography.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the purified protein revealed a single band with a molecular weight of 15.0 kD.Native polyacrylamide gel analysis revealed a band at 30 kD,indicating that TVC exists in solution as a homodimer.Isoelectric focusing showed that TVC was an acidic protein with an isoelectric point of 4.0.TVC was found to lack carbohydrate modifications(based on periodic acid/Schiff staining) and it does not agglutinate mouse red blood cells,suggesting that TVC is not a lectin-like protein.Biological activity assays dem-onstrated that TVC can enhance the proliferation of splenocytes,while it has no stimulatory effects on CD4+and CD8+T cells. TVC markedly increases the proliferation of human peripheral blood lymphocytes in a dose-dependent manner and enhances the production of both nitric oxide and tumor necrosis factor-alpha by lipopolysaccharide-induced murine macrophages.The results indicate that TVC is an immunostimulant that can boost immune response.Comparison of the N-terminal amino acid residues and mass spectrometry results with the protein database revealed no homologous proteins. Bioactive proteins represent an important group of functional agents in medicinal mushrooms.Trametes versicolor (L.) Lloyd is a mushroom frequently used in traditional Chinese medicine for its anti-tumor and immunomodulatory activities. A new immunomodulatory protein from T. versicolor, named TVC, was purified by ammonium sulfate precipitation, ion-exchange chromatography and gel filtration chromatography. sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the purified protein revealed a single band with a molecular weight of 15.0 kD. Native polyacrylamide gel analysis revealed a band at 30 kD , indicates that TVC was in acidic solution with a isoelectric point of 4.0. TVC was found to lack carbohydrate modifications (based on periodic acid / Schiff staining) and it does not agglutinate mouse red blood cells, suggesting that TVC is not a lectin-like protein. Biological activity assays dem-onstrated that TVC can enhance the proliferation of splenocytes, while it has no stimulatory effects on CD4 + and CD8 + T cells. TVC markedly increases the proliferation of human peripheral blood lymphocytes in a dose-dependent manner and enhance the production of both nitric oxide and tumor necrosis factor- alpha by lipopolysaccharide-induced murine macrophages. The results indicate that TVC is an immunostimulant that can boost immune response. Comparison of the N-terminal amino acid residues and mass spectrometry results with the protein database revealed no homologous proteins.