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

<jats:title>ABSTRACT</jats:title><jats:sec><jats:title>Aim</jats:title><jats:p>Vaccines 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: <jats:styled-content style="fixed-case">T</jats:styled-content>‐helper (<jats:styled-content style="fixed-case">Th</jats:styled-content>)1, <jats:styled-content style="fixed-case">Th2</jats:styled-content>, antibody, and cytotoxic <jats:styled-content style="fixed-case">T</jats:styled-content>‐lymphocyte (<jats:styled-content style="fixed-case">CTL</jats:styled-content>) responses. Exogenous antigens are mainly presented to major histocompatibility complex (<jats:styled-content style="fixed-case">MHC</jats:styled-content>) class <jats:styled-content style="fixed-case">II</jats:styled-content> molecules, but are also presented to <jats:styled-content style="fixed-case">MHC</jats:styled-content> class <jats:styled-content style="fixed-case">I</jats:styled-content> 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 <jats:styled-content style="fixed-case">Th1</jats:styled-content> and <jats:styled-content style="fixed-case">CTL</jats:styled-content> responses, resulting in successful intracellular infection and tumor vaccine therapy.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>It 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 <jats:italic>in vitro</jats:italic> model vaccine antigen (ovalbumin, <jats:styled-content style="fixed-case">OVA</jats:styled-content>) cross‐presentation assay.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Among 89 natural compounds, 1,2,3,4,6‐penta‐<jats:styled-content style="fixed-case">O</jats:styled-content>‐galloyl‐β‐<jats:sc>d</jats:sc>‐glucose (<jats:styled-content style="fixed-case">PGG</jats:styled-content>) most enhanced cross‐presentation in dendritic cells. While the expression of <jats:styled-content style="fixed-case">MHC</jats:styled-content> class <jats:styled-content style="fixed-case">II</jats:styled-content> molecules was suppressed, <jats:styled-content style="fixed-case">PGG</jats:styled-content> enhanced the expression of <jats:styled-content style="fixed-case">MHC</jats:styled-content> class <jats:styled-content style="fixed-case">I</jats:styled-content> molecules, restricted to <jats:styled-content style="fixed-case">OVA</jats:styled-content>‐derived peptides.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Restricted <jats:styled-content style="fixed-case">MHC</jats:styled-content> class <jats:styled-content style="fixed-case">I</jats:styled-content> expression resulting from the use of <jats:styled-content style="fixed-case">PGG</jats:styled-content> enhanced cross‐presentation by dendritic cells.</jats:p></jats:sec>