λ-Carrageenan improves the antitumor effect of dendritic cellbased vaccine.

In this study, we investigated the effect of lambda-carrageenan on the maturation and function of dendritic cells (DCs) and its adjuvant effect on DC-based vaccine. We found that lambda-carrageenan dose-dependently decreased the endocytosis of DCs, promoted DC maturation and increased cytokine production through TLR4 mediated signaling pathway. lambda-carrageenan treatment also enhanced the ability of DCs in the stimulating allogenic splenocyte proliferation. In TC-1 tumor mouse model, HPV peptides pulsed lambda-carrageenan-DC (HPV-CGN-DC) significantly inhibited tumor growth compared with control group. The frequencies of CD4(+) and CD8(+) T cells in spleens of tumor mice and their activation status were significantly increased in HPV-CGN-DC group, but the frequencies of natural regulatory T cells and CD11b(+)Gr-1(+) cells were significantly decreased. Further, HPV-CGN-DC induced strong CD8(+) T cell responses, which are negatively correlated with tumor volumes. The results suggested that lambda-carrageenan promoted DC maturation through TLR4 signaling pathway and could be used as the adjuvant in DC-based vaccines.