THE IMMUNOSTIMULATING ACTIVITIES OF ANTITUMOR POLYSACCHARIDES FROM PSEUDOSTELLARIA-HETEROPHYLLA

We have previously shown that a mitogenic fraction (PH-I) separated fr om Pseudostellaria heterophylla exhibits both immunomodulatory and ant i-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 mar kedly suppress the growth of EAT cells in vivo. Mechanistic studies ha ve shown that i.p. injection of PH-I C into mice could enhance the pha gocytic activity of thioglycollate-elicited peritoneal macrophages. Mo reover, PH-I C showed a potent activating effect on the cytotoxic acti vity of natural killer (NK) cells and alloreactive cytotoxic T cells ( Tc) as well as increased the MurIL-2-induced lymphokine activated kill er cell (LAK) activity in vitro. In addition, PK-I C could increase th e number of tumor infiltrating lymphocytes (TILs) in the tumor site of WEHI-164-bearing mice. Finally, i.v. injection of PH-I C significantl y elevated the levels of IFN-gamma and IL-4 in sera of EAT-bearing mic e.