Abstract
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.
Highlights
Immunoadjuvants are used as non-antigenic immune enhancer in vaccine to modify the immune response
We investigated the potential of Poria cocos polysaccharide (PCP) to enhance a T helper 1 (Th1)-mediated cellular immune response against ovalbumin (OVA) in vitro and in vivo
We first analyzed the effect of PCP on bone marrow derived dendritic cells (BMDCs) maturation, BMDCs were harvested from female C57BL/6 mice and cultured with GM-CSF for 6 days, immature BMDCs were cocultured with 100 μg/ml PCP or with 10 μg/ml CpG as a positive control
Summary
Immunoadjuvants are used as non-antigenic immune enhancer in vaccine to modify the immune response. Most of the vaccines are developed using subunit antigen or recombinant proteins, those molecules are less immunogenic than live attenuated pathogens to elicit long-term immunity. Adjuvants are in great need to boost immunogenicity [1]. Aluminum salts (hydroxide or phosphate) was registered for human vaccine since 1930s and had been the only adjuvant proved in clinic until recently. It’s still the most used adjuvant in current human vaccines. This adjuvant preferentially induces antibody response and shows weak or no T helper 1(Th1) or cytotoxic T cell response, which is essential for protection against many viruses or intracellular bacteria as well as cancerous cells.
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