[Experimental studies on immunostimulatory effects of the Isatis indigotica polysaccharide].

Polysaccharides extracted from the root of Isatis indigotica (IIP, 50 mg/kg.d, ipx8d) significantly increased the weight of spleen and number of white blood cell and lymphocyte in peripheral blood in normal ICR mice, and antagonized the immunosuppressive actions of hydrocortisone. There were marked potentiating effects on delayed hypersensitivity reaction induced by 2, 4-dinitrochlorobenzene in normal NIH mice treated with IIP as well as in immunodepressed mice induced by cyclophosphamide. By administration of IIP, the percentage of ANAE+ lymphocytes stained with acid alpha-naphthyl acetate esterase method were significantly increased in peripheral blood of normal ICR mice, and the decreases in number of ANAE+ lymphocytes in mice induced by hydrocortisone were prevented to a certain extent. But IIP could not enhance Con A-induced lymphocyte proliferation of C57BL mouse spleen cells in vitro measured with MTT colorimetric assay. In addition, the plaque forming cells in 5 x 10(6) splenocytes of NIH mice treated with IIP were higher than that of the control group (P less than 0.01). IIP could also elevate the clearance rate of intra-venous charcoal particles in normal mice, i.e., stimulated the phagocytic activity of macrophages. The result indicates that IIP is capable of increasing humoral and cellular immune functions and enhancing the functions of reticuloendothelial system, and might be a good immunopotentiator.