Polysaccharides from Astragalus membranaceus elicit T cell immunity by activation of human peripheral blood dendritic cells.

Astragalus membranaceus is a widely used herbal medicine in Asia. It has been recognized as possessing various biological properties, however, studies on the activity of the A. membranaceus polysaccharide (AMP), a major component of A. membranaceus, on human peripheral blood dendritic cells (PBDCs) have not been thoroughly investigated. In this study, we found that AMP induced changes in dendritic morphology and the upregulation of activation marker expression and inflammatory cytokine production in human blood monocyte-derived dendritic cells (MDDCs). The AMP promoted the activation of both blood dendritic cell antigen 1 (BDCA1) and BDCA3 PBDCs. AMP-induced secretion of cytokines in the peripheral blood mononuclear cells (PBMCs) was mainly due to PBDCs. Finally, activated BDCA1 and BDCA3 PBDCs by AMP elicited proliferation and activation of autologous T cells, respectively. Hence, these data demonstrated that AMPs could activate dendritic and T cells in human blood, and may provide a new direction for the application of AMPs in the regulation of human immunity.