Lycium barbarum polysaccharides as an adjuvant for recombinant vaccine through enhancement of humoral immunity by activating Tfh cells.

Lycium barbarum polysaccharides (LBP) have been shown to play a variety of immune-modulatory functions which include activation of T and B cells. Follicular helper T (Tfh) cells are now recognized as a subset of helper T cells which regulate the multiple stages of B cell maturation and function. In our current study, we found that LBP were able to activate CXCR5+PD-1+ Tfh cells and induce IL-21 secretion. At the same time LBP also promoted the formation of germinal centers (GC) and production of GL-7+B220+GC B cells. LBP as an adjuvant could increase generation of rAd5VP1-induced Tfh cells. Our results indicate that LBP might enhance T cell-dependent Ab responses by acting as an adjuvant for the generation of Tfh cells. Future vaccine designs might therefore be targeted to induce strong antigen-specific Tfh responses in order to boost its protective effects.