Résumé
Objective:To investigate the antigen-sparing effects of crude polysaccharides from Cistanche deserticola Y. C.Ma (CPCD) for influenza virus vaccine (IVV). Methods:ICR mice were immunized subcutaneously with CPCD combined with different doses of IVV (0.01 μg and 0.1 μg). Hemagglutinin inhibition (HI) assay was used to detect HI titers in serum samples. Indirect ELISA was performed to detect the levels of specific IgG antibodies and their subtypes in serum samples. The proliferation of splenic lymphocytes was detected by MTT assay. The percentages of CD4 + , CD8 + and CD44 + T cells and the levels of IFN-γ in splenic cells isolated from the vaccinated mice were analyzed by flow cytometry. Results:CPCD significantly increased HI titers (234.67±47.70 vs 149.33±47.70, P<0.05), promoted the production of IgG ( A450 value: 1.16±0.63 vs 0.30±0.21, P<0.05) and IgG1 ( A450 value: 1.09±0.60 vs 0.26±0.21, P<0.05) and enhanced splenic lymphocyte proliferation ( P<0.05). CPCD also significantly up-regulated the expression of CD4 + [(41.97±4.58)% vs (25.43±1.48)%, P<0.05], CD8 + [(12.67±0.33)% vs (9.02±1.07)%, P<0.05], CD4 + CD44 + [(11.77±0.69)% vs (8.64±0.71)%, P<0.05] and CD8 + CD44 + [(6.70±0.67)% vs (4.66±0.39)%, P<0.05] T cell subsets as well as the secretion of IFN-γ in CD4 + [(1.36±0.07)% vs (0.87±0.06)%, P<0.05] and CD8 + [(2.09±0.20)% vs (1.42±0.08)%, P<0.05] T cells. In addition, there was no significant difference between CPCD combined with low-dose IVV group and high-dose IVV alone group ( P>0.05), implying a 10-fold antigen sparing. Conclusions:CPCD, as an adjuvant for influenza virus vaccine, could enhance humoral and cellular immune responses and reduce antigen dose, which might be a potential adjuvant for seasonal or pandemic influenza vaccines.