Type II arabinogalactan from Anoectochilus formosanus induced dendritic cell maturation through TLR2 and TLR4.

ABSTRACT

BACKGROUND: Polysaccharides, considered as immunomodulators with the capacity to activate immunity against microbial pathogens and tumors, have been employed for their dietary and medical benefits. PURPOSE: This study investigated the immunomodulatory effect of polysaccharide such as type II arabinogalactan from Anoectochilus formosanus (AGAF) on dendritic cell (DC) maturation and the underlying molecular mechanisms. METHODS AND RESULTS: Exposing DCs to AGAF induces cell maturation, which is characterized by the upregulation of CD86, CD83, CD80, CD40, and MHC class I and class II expression through flow cytometry analysis and morphological change without cytotoxicity. In addition, AGAF-triggered DC2.4 cells were involved in priming T-cell activation in vitro and in vivo. Transfection of toll-like receptor (TLR) 2 proteins and TLR4 siRNA suppressed DC maturation, suggesting that AGAF induced DC maturation through TLR2 and TLR4. CONCLUSION: These findings indicate that AGAF may be a potentially effective immunomodulator in stimulating DC maturation.