Immunomodulatory activity of polysaccharide isolated from Angelica sinensis

The immunomodulatory activities of an Angelica sinensis polysaccharide (AP), purified from the fresh root of A. sinensis Diels, were investigated in vitro in relation to the specificity to immune cells. AP consisted of rhamnose, arabinose, mannose, glucose, galactose with the molar ratio of 1.00:4.54:2.98:11.09:7.45. Cell proliferation results showed that proliferation of total spleen cells, macrophages and T cells were promoted by the action of AP. The treatment of AP increased the production of IL-2 and IFN-gamma, while that of IL-4 was decreased. RT-PCR analysis displayed that the IL-2 and IFN-gamma gene expression were enhanced but the IL-4 gene expression was decreased. Some differences in cytokines secretion pattern were also detected, the expression of IFN-gamma was rapidly augmented while that of IL-2 responded later. The flow cytometry results showed that the percentage of CD4(+)T cell in total spleen cells was remarkably increased by AP, while that of CD8(+)T cell was slightly decreased. In conclusion, AP has immunomodulatory activity by regulating expression of Th1 and Th2 related cytokines. The time-effect relation of cytokines response also suggests that macrophages and natural killer cells involved in nonspecific immunity were primary activated, and helper T cell were secondarily affected by AP.