Improvement of immune responses to influenza vaccine (H5N1) by sulfated yeast beta-glucan

In this study, the adjuvant activity of sulfated glucan from saccharomyces cerevisiae (SGSC) was investigated. sGSC had molecular weight of 12.9 kDa and degrees of sulfation of 0.16. The effects of SGSC on the splenic lymphocyte cells of mice were measured in vitro. The results showed that SGSC could significantly promote lymphocyte proliferation singly or synergistically with Con A and LPS, and stimulate the cells to secrete IL-2 and INF-γ. The adjuvant activity of SGSC was researched in BALB/c mice inoculated with inactivated H5N1vaccine in vivo. The results showed that SGSC could significantly enhance lymphocyte proliferation, effectively increase the percentage of CD4+ T cells, decrease the percentage of CD8+ T cells, and elevate the CD4+/CD8+ ratio; enhance the HI antibody titre, and promote the production of IL-2, INF-γ, IL-4 and IL-6 at medium level. These results indicated that sulfated glucan showed an excellent adjuvant effect on H5N1vaccine in a mouse model. Therefore, SGSC could be used as an effective immune adjuvant for an inactivated H5N1vaccine.