Evaluation of the Immunomodulatory Activities of the Aqueous Extract and the BetaD-Glucan-Rich Polysaccharide Fraction of Pleurotustuberregium(Pleurotaceae)

ABSTRACT

Mushroom cuisines are global delicacies and have been used for decades, not only as food, but mostly for the health benefits which are claimed or scientifically proven. The present study explored the immunomodulatory activities of the hot aqueous extract of a local oyster mushroom, Pleurotustuberregium (Fr.) Singer (Pleurotaceae) (PT) and its β–D-Glucan-Rich Polysaccharide fraction (BGP).The effects of the aqueous extract (PT) and the β–D-Glucan-Rich Polysaccharide fraction (BGP) were tested on some specific and non-specific immune responses in immune-competent mice and in culture of RAW 264.7 macrophage cells. The effect of the PT and BGP on specific cell mediated immune response was investigated by the delayed type hypersensitivity response (DTHR) whilethe effect of the extract on specific humoral immune responses of treated mice was determined by prime-boost immunization protocol using ovalbumin as antigen and followed by the determination of antibody titers in the sera using the enzyme-linked immunosorbent assay (ELISA).Their effect on non–specific immune responses was determined by the colloidal carbon-clearance assay in mice. The effect of BGP on functional maturation and activation of the monocytic cells was also determined by measuring the level of tumour necrosis factor (TNF)-α and inducible oxygen (iNO) expressed into culture supernatant using cytokine capture ELISA and Griess reagent respectively.Short-term oral administration of PT (100, 200 and 400mg/kg) or BGP (100 and 200mg/kg) elicited a dose-related increase in DTHR and increased the mean phagocytic clearance of colloidal carbon in mice as much as 7 – 10 fold when compared to the clearance in the untreated group of mice. In a homologous prime-boost immunization schedule, oral supplementation with PT (100, 200 and 400mg/kg) or BGP (100 and 200mg/kg) significantly (P