The Effects Of Lycium Barbarum Polysaccharide On The Expression Of MICA In Leukemia Cell Lines And NK Cell Cytotoxicity

Objective:Minimal residual disease in leucamia patients are the root cause of resulting in patients with relapsed, because of immunotherapy is to activate the patients’ immune responses, can effectively remove minimal residual leukemia cells. As immune effected cells in the body’s innate immune, NK cells played an important role in immune surveillance, early in the process of anti-tumor and anti-infection, constitute the first anti-tumor immune defense line, NKG2D is important activated receptor of NK cells, with the targeted cell surface ligand cross-linking can trigger cytotoxic activity of NK cells, produced the killing function to targeted cells. Studies have showen that leukemia cells maybe reduced the expression of MICA ligand to evade NK cells’ recognition, thus occured immune escape, caused NK cells to weaken or not to play their effective immune destruction. Therefore, increasing the expression of MICA in leukemia cells, enhancing cytotoxicities of NK cells could become one of the effective ways for leukemia immune therapy. The experiment is to analyze the effects of Lyciumbarbarum polysaccharide on the expression of MICA in leukemia cell lines and NK cell cytotoxicities, and to look for new targets of immunotherapy of leukemia.Methods:With three concentrations of LBP (6mg/ml、8mg/ml、10mg/ml)cultured in HL-60cells48hours as experimental group(including three group), the control group wasn’t treated by LBP, the expression of MICA in HL-60cells of every group were assayed by flow cytometry; at different effect-to-target, cultured NK/HL-60cells20hours, MTT assay was detected to the cytotoxicities of NK cells against HL-60cells of every group.Results:Flow cytometry showed the expression of MICA in HL-60cells of experimental group (treated by6mg/ml、8mg/ml、10mg/ml of LBP)were(8.47±0.25)%、(10.48±0.68)%、(11.73±0.62)%, compared with the control group (5.75±0.34)%, the difference was statistically significant(P<0.05); with concentrations of LBP increasing, the expression of MICA is rising. MTT assay showed at5:1、10:1、20:1of effect-to-target, when concentrations of LBP was6mg/ml、8mg/ml、10mg/ml，the cytotoxicities of NK cells againt HL-60cells were higher than control group, the difference was statistically significance (P<0.05); and they are depended on the concentrations of LBP.Conclusion:1. LBP could increase the expression of MICA in HL-60cells, with concentrations of LBP increasing, the expression of MICA is rising.2. LBP could enhance the cytotoxicities of NK cells against HL-60cells, showing concentrations-depence.3. By increasing the level of MICA expression, may important significance to clear minimal residual disease and reduce the recurrence of leukemia.