Herbal plant‐derived compound, 1,2,3,4,6‐penta‐O‐galloyl‐β‐d‐glucose, increases cross‐presentation by dendritic cells

Abstract

ABSTRACTAimVaccines have made great contributions to human welfare, and can be used even more effectively with adjuvants. The immune‐inducible effects of adjuvants are classified into four categories: T‐helper (Th)1, Th2, antibody, and cytotoxic T‐lymphocyte (CTL) responses. Exogenous antigens are mainly presented to major histocompatibility complex (MHC) class II molecules, but are also presented to MHC class I molecules via the antigen cross‐presentation process in dendritic cells. The enhancement of cross‐presentation of an injected vaccine antigen by an adjuvant leads to Th1 and CTL responses, resulting in successful intracellular infection and tumor vaccine therapy.MethodsIt is widely known that herbal medicines have strong immune response effects. With this in mind, we developed a novel vaccine adjuvant from natural compounds used in herbal medicine, through an in vitro model vaccine antigen (ovalbumin, OVA) cross‐presentation assay.ResultsAmong 89 natural compounds, 1,2,3,4,6‐penta‐O‐galloyl‐β‐d‐glucose (PGG) most enhanced cross‐presentation in dendritic cells. While the expression of MHC class II molecules was suppressed, PGG enhanced the expression of MHC class I molecules, restricted to OVA‐derived peptides.ConclusionRestricted MHC class I expression resulting from the use of PGG enhanced cross‐presentation by dendritic cells.