NK细胞与K562细胞之间相互免疫编辑作用及其对NK细胞杀伤活性的影响

目的：探讨NK细胞与K562细胞混合培养前、后其杀伤活性的变化及分子机制。方法：流式细胞仪检测NK细胞与K562细胞混合培养前、后细胞表面相应分子的变化，LDH释放法测定效靶比20∶1时NK细胞对K562细胞的杀伤活性。结果：相互编辑前，K562细胞表面MICA/MICB的表达率为(79.90±0.87)%，NK细胞表面NKG2D、KIR2DL1和KIR3DL1的表达率分别为(98.27±0.67)%、(45.70±1.22)%和(35.60± 1.35)%。相互编辑后，K562细胞表面MICA/MICB和NK细胞表面NKG2D的表达率分别为（35.56±1.01）和（34.67±3.88）%，均明显低于编辑前（Ｐ=0.000）；NK细胞表面KIR2DL1和KIR3DL1的表达率分别为（47.20±1.08）%和（34.03±1.20）%，与编辑前比较差异均无显著性(Ｐ>0.05)。效靶比20∶1时，NK细胞对编辑后的K562细胞的杀伤活性为(24.07±0.58)%，编辑后的NK细胞对K562细胞的杀伤活性为(16.95±2.00)%，均明显低于编辑前NK细胞对K562细胞的杀伤活性［(54.03±3.46)%］(Ｐ＝0.000)。结论: NK细胞与K562细胞持续性接触后，双方发生了相互免疫编辑作用；NK细胞的杀伤活性下降，其分子机制是细胞表面相应的配受体发生了变化。

Reciprocal immunoediting between NK cells and K562 cells and its effect on NK cell-mediated cytotoxicity

Objective To analyze the changes of cytotoxicity mediated by NK cells after 24 h coculture with K562 cells and the molecular mechanism. Methods The expressions of MICA/MICB on K562 cells, KIR2DL1, KIR3DL1, NKG2D on NK cells were analyzed by flow cytometry. Cytotoxicity was detected by LDH releasing assay. Results Before editing,the expression rate of MICA/MICB on K562 cells was (79.90±0.87)%, the expression rates of NKG2D,KIRZDL1, and KIR3DL1 on NK cells were (98.27±0.67)%, (45.70±1.22)% and (35.60±1.35)%,respectively.After editing,the expression rates of M1CA/M1CB on K562 cells and NKG2D on NK cells were (35.56±1.01)% and (34.67±3.88)%,respectively;compared with before editing,there was significant difference(P=0.000).The expression rates of KIR2DL1 and KIR3DL1 on NK cells were (47.20±1.08)% and (34.03±1.20)%,compared with before editing,there was no signficant difference(P>0.05).The cytotoxicities against K562 cells by edited NK cells and against the edited K562 cells by NK cells were(24.07± 0.58)% and (16.95±2.00)% at an effector-to-target (E/T) ratio of 20∶1, both were lower than the cytotoxicity against K562 cells by NK cells (54.03%±3.46%), the differences were significant (P=0.000). Conclusion Reciprocal immunoediting between NK cells and K562 cells induced by 24 h coculture leads to decreased cytotoxicity of NK cells. The potential molecular mechanism is the changes of NKG2D and MICA/MICB expressions.