Effects of Astragalus polysaccharides and astragalosides on the phagocytosis of Mycobacterium tuberculosis by macrophages

The herb Astragalus membranaceus is used in traditional Chinese medicine to boost immunity. This study investigated the effects of Astragalus polysaccharides (APS) and astragalosides (AS) on the phagocytosis of Mycobacterium tuberculosis by macrophages. Peritoneal macrophages were obtained by peritoneal lavage from mice stimulated by starch gravy culture medium and cultured with M. tuberculosis and varying concentrations of APS and AS. Phagocytotic activity was measured using a real-time polymerase chain reaction assay to detect M. tuberculosis DNA. Levels of interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha secreted by activated macrophages in the culture supernatant were determined using an enzyme-linked immunosorbent assay. Macrophage phagocytotic activity and secreted cytokine levels were significantly increased after treatment with APS and AS. This study provides evidence that APS and AS have strong promoting effects on the phagocytosis of M. tuberculosis by macrophages and the secretion of interleukin-10, interleukin-6 and tumour necrosis factor-a by activated macrophages.