Polysaccharides isolated from Açaí fruit induce innate immune responses

PLoS One. 2011 Feb 28;6(2):e17301. doi: 10.1371/journal.pone.0017301.

Abstract

The Açaí (Acai) fruit is a popular nutritional supplement that purportedly enhances immune system function. These anecdotal claims are supported by limited studies describing immune responses to the Acai polyphenol fraction. Previously, we characterized γδ T cell responses to both polyphenol and polysaccharide fractions from several plant-derived nutritional supplements. Similar polyphenol and polysaccharide fractions are found in Acai fruit. Thus, we hypothesized that one or both of these fractions could activate γδ T cells. Contrary to previous reports, we did not identify agonist activity in the polyphenol fraction; however, the Acai polysaccharide fraction induced robust γδ T cell stimulatory activity in human, mouse, and bovine PBMC cultures. To characterize the immune response to Acai polysaccharides, we fractionated the crude polysaccharide preparation and tested these fractions for activity in human PBMC cultures. The largest Acai polysaccharides were the most active in vitro as indicated by activation of myeloid and γδ T cells. When delivered in vivo, Acai polysaccharide induced myeloid cell recruitment and IL-12 production. These results define innate immune responses induced by the polysaccharide component of Acai and have implications for the treatment of asthma and infectious disease.

Publication types

  • Evaluation Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arecaceae / chemistry*
  • Cattle
  • Cells, Cultured
  • Fruit / chemistry*
  • Genes, T-Cell Receptor alpha
  • Humans
  • Immunity, Innate / drug effects*
  • Immunity, Innate / genetics
  • Immunity, Innate / physiology
  • Lymphocyte Activation / drug effects
  • Mice
  • Mice, Inbred C3H
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Myeloid Differentiation Factor 88 / genetics
  • Phenols / pharmacology
  • Polysaccharides / isolation & purification*
  • Polysaccharides / pharmacology*
  • Toll-Like Receptor 4 / genetics
  • Up-Regulation / drug effects

Substances

  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • Phenols
  • Polysaccharides
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4