Oral Administration of Phosphorylated Dextran Regulates Immune Response in Ovalbumin-Immunized Mice

Abstract

Phosphorylated dextran (P-Dex) is an acidic polysaccharide that functions as an immune adjuvant. P-Dex is known to regulate immune response by maintaining a balance between Th1 and Th2 cells in vitro, and thus may also be important in the control of allergic reactions. In the current study, we report the optimum conditions required for the efficient phosphorylation of dextran without toxicity. We found that when dextran was heated at 160°C for 24 h in phosphate buffer (pH 5.0), the resulting P-Dex demonstrated the highest phosphorus content (6.8%). We also report that P-Dex enhances mitogenic activity in mouse splenocytes and induces expression of CD69 and CD86 on the surface of B cells and dendritic cells (DC) in vitro. Oral administration of P-Dex to ovalubmin (OVA)immunized mice was found to reduce antigen-induced cell proliferation and suppress the expression of CD86 on Th2-inducing DC via exogenous OVA stimulation. P-Dex was also found to increase IL-10 expression in the splenocytes of treated mice. These findings suggest that oral administration of P-Dex increases immunological tolerance and improves the specificity of immunological response to specific antigens.

Phosphorylated Radix Cyathulae officinalis Polysaccharides Act as Adjuvant via Promoting Dendritic Cell Maturation

“…An ideal adjuvant can stimulate both Th1 and Th2 responses to induce protective immunity against certain infectious diseases is desirable. Nagasawa et al (2010) have reported that phosphorylated dextran (P-Dex) functions as an adjuvant that can modulate immune responses by maintaining a balance between Th1 and Th2 cells in vitro [ 18 ]. Kawashima et al (2012) have also demonstrated that fucoidan as a sulfated polysaccharide can enhance an immunobalanced Th1/Th2 immune response in ovalbumin-immunized mice, as indicated by the significant production of both Th1/Th2 cytokines [ 35 ].…”

“…The extraction and purification of RCPS was performed as previously described [ 18 ]. Briefly, the dry powder of RC was extracted in water three times under reflux.…”

“…The spleens were removed on Day 14 after the boost. Single cells suspensions were prepared according to previous report [ 18 ]. Splenocytes numbers were counted by Trypan blue dye exclusion method.…”

“…Cell viability exceeded 95%. The splenocyte proliferation level was measured by Cell counting Kit-8 (Beyotime, Haimen, China) according to the manufacturer’s instructions [ 18 , 20 ]. The optical density (OD) was determined by a microplate reader (Model 680, Bio-Rad) at 450 nm.…”

“…Oral administration P-Dex can significantly enhance the specificity of immunological responses in ovalbumin-immunized mice [ 16 ]. Furthermore, Nagasawa et al (2010) have demonstrated that phosphorylated dextran (P-Dex) can improve the immunological response to specific antigens [ 18 ].…”