The immunostimulating activities of anti-tumor polysaccharides from Pseudostellaria heterophylla.

We have previously shown that a mitogenic fraction (PH-I) separated from Pseudostellaria heterophylla exhibits both immunomodulatory and anti-tumor activities. In the present study, PH-I was further purified by gel filtration chromatography and the resulting three fractions (PH-I A, PH-I B and PH-I C) were assessed for their anti-tumor activity in vivo. It was found that fraction PH-I C from P. heterophylla could markedly suppress the growth of EAT cells in vivo. Mechanistic studies have shown that i.p. injection of PH-I C into mice could enhance the phagocytic activity of thioglycollate-elicited peritoneal macrophages. Moreover, PH-I C showed a potent activating effect on the cytotoxic activity of natural killer (NK) cells and alloreactive cytotoxic T cells (Tc) as well as increased the MurIL-2-induced lymphokine activated killer cell (LAK) activity in vitro. In addition, PH-I C could increase the number of tumor infiltrating lymphocytes (TILs) in the tumor site of WEHI-164-bearing mice. Finally, i.v. injection of PH-I C significantly elevated the levels of IFN-gamma and IL-4 in sera of EAT-bearing mice.