Abstract: The aim of this study was to investigate the effects of astragalus polysaccharide (APS) nanoparticle (using chitosan as carrier) with low dispersion on immune function of diabetes mellitus (DM) mice.The DM low immunity mice model was developed by injecting cephalosporins and cyclophosphamide.The low dispersion chitosan was prepared by enzymatic method.The low dispersion chitosan APS nanoparticle was then prepared by ultrasonic embedding.The prepared sample was gavaged to the developed mice model,one time a day and for 30 d.The levels of IgM,IgG and INF-γ of DM mice serum were determined by ELISA method.The nonspecific immune function of DM mice was determined by carbon clearance method.The delayed type hypersensitivity (DTH) was determined by ear swelling method and the spleen lymphocyte proliferation rate was determined by MTT assay and was used to reflect the cellular immune function.The experimental results showed that the 350 mg/(kg·d) LCA group significantly increased the secretion of serum IgM and IgG,significantly reduced the INF-γ expression,enhanced the carbon clearance rate,improved the mice DTH,improved spleen lymphocyte proliferation reaction.It indicated that appropriate doses of low dispersion chitosan APS nanoparticle can improve DM mice humoral immunity,nonspecific immunity and cellular immunity function,can reduce the incidence of DM complicated with infection.The effect of low dispersion chitosan APS nanoparticle was better than that of pure APS.

Key words: chitosan, astragalus polysaccharides, nanoparticles, DM mice, immune function