The immunological activity of Lycium barbarum polysaccharides liposome in vitro and adjuvanticity against PCV2 in vivo

• The average diameters of liposomes (LBPL, BL) and liposome-formulated vaccines (LBPL-PCV2, BL-PCV2) were less than 200 nm and stable.
• LBPL could significantly promote splenocyte proliferation and the cytokine secretion of macrophages in vitro.
• LBPL as a vaccine adjuvant has good improvement effect on immune responses against PCV2 in vivo.

In previous researches, the results showed that Lycium barbarum polysaccharides (LBP) encapsulated with liposome could enhance the immune activity of LBP. Therefore, the present study was designed to investigate the effects of LBPL on spleen lymphocytes and macrophages of mice in vitro and evaluate the immunological adjuvant activity of PCV2 vaccine in vivo. The results showed that LBPL could significantly promote splenocyte proliferation synergistically with PHA or LPS, increase the ratio of CD4+ to CD8+ T cells and promote the cytokine secretion of macrophages; enhance PCV2-specific IgG antibody responses, promote Th1 cytokines (IFN-γ and TNF-a) and Th2 cytokine (IL-4) secretion. The histomorphological observation of spleen demonstrated that LBPL as a vaccine adjuvant also has good improvement and stimulating effect on the immune organ.