Abstract: ObjectiveTo study the effects of polyporus polysaccharide(PPS) combined with interleukin15(IL15) on the proliferation of human peripheral blood mononuclear cells (PBMC)， and to further clarify the effect on its killing activity and mechanism to chronic myeloid leukemia K562 cells.MethodsDensity gradient method was used to separate PBMC， then IL2， IL15， PPS， PPS combined with IL2 and PPS combined with IL15 were used to stimulate PBMC to proliferate PBMC respectively， so as to acquire the effecter cells. Finally， FCM was used to detect the immunophenotype of T cells， NK cells activated in PBMC; double antibody sandwich ELISA method was performed to detect the levels of IFNγ and TNFα in cell culture supernatant; MTT colorimetry method was performed to detect the cytotoxic effect of effector cells to target cells. ResultsThe combination of PPS and IL15 could synergistically stimulate T cells and NK cells’ proliferation in PBMC; it could raise the levels of cytokines IFNγ and TNFα in effector cell culture supernatant; Also it could enhance the cytotoxic effect of effector cells to target cells in a timedependent manner. ConclusionThe combination of PPS and IL15 can improve the cytotoxicity effect of PBMC on cell strain K562 which presented at the increase of IR of the tumor cells’ proliferation. The killing mechanism may be caused by the proliferation of T cells and NK cells stimulated by the combination of PPS and IL15 and the improved levels of IFNγ and TNFα in cell culture supernatant.

Key words: leukemia, myeloid； polyporus polysaccharide, interleukin15 , monocytes ;K562 cells, killing activity