Influence of interleukin in inducing the cytotoxicity of NK cells against human multiple myeloma RPMI 8226 cells and its mechanism

HAN Lu; GAO Quanli; SONG Yongping; ZHOU Jian

doi:10.3969/j.issn.1002-266X.2016.12.001

Abstract：Objective To investigate the influence of interleukin ( IL) in inducing the cytotoxicity of natural killer ( NK) cells against the activity of human multiple myeloma RPMI 8226 and the correlated molecular mechanisms.Methods The human peripheral blood mononuclear cells ( PBMC) were randomly divided into 6 groups:the control group ( simple culture medium), IL-2 group (added with 1000 U/mL IL-2), IL-7 group (40 ng/mL IL-7), IL-21 group (20 ng/mL IL-21), IL-2+IL-7 group (1000 U/mL IL-2+40 ng/mL IL-7) and IL-2+IL-7+IL-21 group (1000 U/mL IL-2, 40 ng/mL IL-7+20 ng/mL IL-21) .They were all cultured for 5 days.The proportion of NK cells and the expression of activated receptors (NKG2D, NKp46, NKp44 and NNKp30) were measured by flow cytometry.The expression of NKG2D mRNA, NKP46 mRNA and NKP30 mRNA was measured by RT-PCR.Cytotoxicity of NK cells against RPMI8226 cells was ana-lyzed by CFSE/PI double staining.Results Except the IL-7 group, the proportion of NK cells and the expression of NKG2D in the other groups were increased as compared with those of the control group (all P＜0.05).No significant difference in the gene expression of NKG2D, NNKp46 and NKp30 was found among these groups (all P＞0.05).The cell-killing rate of NK cells on RPMI8226 cells in the control group was 2.13%±0.42%, and that in the IL-2 group was 58.73%±1.80%, the IL-7 group was 1.90%±0.60%, the IL-21 group was 14.43%±1.22%, the IL-2+IL-7 group was 34.27%±2.35%, and the IL-2+IL-7+IL-21 group was 37.47%±0.60%.Significant difference was found in the cell-killing rate between the control group and the other groups ( all P＜0.05) .Conclusions The single factor IL-2, IL-21, double-factor IL-2+IL-7 and multi-factor IL-2+IL-7+IL-21 can enhance the cytotoxic effect of NK cells against RP-MI 8226 cells, and the single factor IL-2 is the best.The increased number of NK cells and the expression of cell surface activation acceptor (NKG2D) may be the possible mechanism.