NK细胞杀伤人骨髓瘤RPMI8226细胞的活性及其可能的机制

Cytotoxicity of NK cells against RPMI 8226 cells and its possible mechanism

目的:研究同种异体NK细胞对人骨髓瘤RPMI 8226细胞的杀伤活性及其可能的机制。方法:LDH释放法检测NK细胞对RPMI 8226细胞和人白血病K562细胞的杀伤活性,流式细胞术和RT-PCR法分别检测K562和RPMI 8226细胞中NKG2D配体和HLA-Ⅰ类分子的表达;阻断K562和RPMI 8226细胞中NKG2D配体的表达后,检测NK细胞的杀伤活性。结果:NK细胞对RPMI 8226靶细胞的杀伤活性明显低于对K562靶细胞的杀伤(P<0.01)。K562细胞高表达NKG2D配体,不表达HLA-Ⅰ类分子;RPMI 8226细胞低表达NKG2D配体,高表达HLA-Ⅰ类分子,其HLA基因型为A 01,66;B 58,58;Cw 03,06。阻断NKG2D配体后NK细胞杀伤K562细胞的活性明显降低(P<0.01),而杀伤RPMI 8226细胞的活性无明显改变;阻断HLA-Ⅰ类分子,NK细胞杀伤K562细胞的活性无变化,而杀伤RPMI 8226细胞的活性明显提高(P<0.01)。结论:NK细胞杀伤RPMI 8226细胞的活性较低,其机制与RPMI 8226细胞高表达HLA-Ⅰ类分子、低表达NKG2D配体有关。

Objective： To observe the cytotoxicity of allogenic natural killer（NK） cells against myeloma RPMI 8226 cells and its possible mechanism.Methods： Cytotoxicity of NK cells against RPMI8226 and K625 cells was analyzed by LDH releasing assay.The expressions of NKG2D ligands and HLA-Ⅰ molecule on K562 and RPMI 8226 cells were measured by flow cytometry and RT-PCR,respectively.In the blocking experiments,the target cells were treated by monoclonal antibodies against HLA-Ⅰ molecule and NKG2D ligands before cytotoxicity of NK cells were examined.Results： The cytotoxicity of NK cells against RPMI 8226 target cells was lower than that against K562 cells.K562 cells expressed high levels of NKG2D ligands and did not express HLA-Ⅰ;RPMI8226 cells expressed low levels of NKG2D ligands and high levels of HLA-Ⅰ.The HLA-Ⅰ genotypes of RPMI 8226 cells were A 01,66;B 58,58;and Cw 03,06.NKG2D ligand blocking experiments revealed that the cytotoxicity of NK cells against K562 cells was greatly inhibited,but that against RPMI 8226 cells was not affected.Conversely,the cytotoxicity of NK cells against RPMI 8226 cells was obviously improved,and that against K562 cells was not affected when HLA-Ⅰ molecule was shaded.Conclusion： Weak expressions of NKG2D ligands and high expression of HLA-Ⅰ molecule may contribute to the reduced cytotoxicity of NK cells against myeloma RPMI 8226 cells.