New protein PCiP from edible golden oyster mushroom (Pleurotus citrinopileatus) activating murine macrophages and splenocytes

A new immunomodulatory protein (PCiP) was purified from an edible golden oyster mushroom (Pleurotus citrinopileatus) by extraction with 5% (v/v) cold acetic acid in the presence of 0.1% (v/v) 2-mercaptoethanol, followed by ammonium sulfate fractionation, DE-52 and MonoQ anion-exchange chromatography. Electrophoresis assays demonstrated that the molecular mass of PCiP was approximately 15.0kDa and its pI was around 5.2. PCiP is a simple protein without carbohydrate, and cannot agglutinate mouse red blood cells, suggesting PCiP is not a lectin. In addition, PCiP (5-20 mu g mL(-1)) alone activated murine splenocytes, and markedly increased their proliferation and gamma-interferon (IFN-gamma secretion, but suppressed MTT metabolization, while murine splenocytes were simultaneously stimulated by the mitogen concanavalin A (ConA). Furthermore, PCiP (5-20 mu g mL(-1)) directly activated murine macrophages and increased the production of both the nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha by RAW 264.7 macrophages. These findings suggest that PCiP could strengthen both the innate and adaptive responses of its host. (c) 2007 Society of Chemical Industry.