Poria cocos polysaccharide induced Th1-type immune responses to ovalbumin in mice

In the present study, we evaluated adjuvant potential of Poria cocos polysaccharide (PCP) on the Th1-type immune responses of C57/BL6 mice against ovalbumin (OVA). We first determined the effect of PCP on maturation of murine bone marrow derived dendritic cells (BMDCs), PCP significantly upregulated surface expression of MHCII, CD40, CD80, CD86 and enhanced production of IL-6 and IL-12p40. In addition, PCP affected receptor-mediated endocytosis, but not pinocytosis in BMDCs. Furthermore, OVA + PCP immunization induced specific cytotoxic CD8+ T cell killing of OVA (257-264) peptide pulsed cell. When mice were immunized subcutaneously in a week interval with OVA + PCP. Serum were collected for measuring OVA-specific antibody and splenocytes were harvested for analyzing CD69, IFN-γ ELISpot and cytokines production. The result indicated that OVA-specific IgG, IgG2a and IgG1 antibody levels in serum were significantly elevated by PCP compared with control. PCP increased OVA-specific IFN-γ-secreting CD8+, CD4+ T cells, promoted CD8+ T cell proliferation and up-regulated Th-1 type (IFN-γ, IL-2) cytokine production. In conclusion, data suggest that PCP enhanced cellular immune response and possess potential as a vaccine adjuvant for Th1 immune response.