活化性杀伤细胞免疫球蛋白样受体阳性的NK细胞对靶细胞的杀伤作用

目的 研究活化性杀伤细胞免疫球蛋白样受体(KIR)KIR2DS1阳性的自然杀伤(NK)细胞对急性髓系白血病(AML)靶细胞的杀伤作用;并探讨NK细胞KIR及人类白细胞抗原Cw位点(HLA-Cw)与靶细胞HLA-Cw错配对靶细胞的杀伤机制.方法 获取健康供者的外周血,经Dnyal磁珠负选高纯度NK细胞;取初治确诊的AML患者新鲜骨髓液,分离后的白血病细胞作为靶细胞.用抗CD158a和CD158b单克隆抗体封闭NK细胞抑制性KIR(如:KIR2DL1、KIR2DL2和KIR2DL3),并用噻唑蓝(MTT)比色法分别检测抑制性KIR封闭前和封闭后NK细胞对靶细胞的杀伤作用.采用聚合酶链反应和顺序特异性引物(PCR-SSP)基因分型技术分别检测NK细胞及靶细胞的KIR基因和HLA-Cw;根据HLA-Cw将NK细胞和靶细胞分别分为C1组(表达HLA-Cw 01、03、07、08、12、14、16分子)、C2组(表达HLA-Cw02、04、05、06、15、17、18分子)和C1/C2组(既表达C1组的等位基因又表达C2组的等位基因).结果 分选后的NK细胞经流式细胞仪检测,其纯度为(90.8±6.08)%;NK细胞抑制性KIR封闭后与封闭前比较,其对靶细胞的杀伤作用明显增强(t=-3.00,P=0.005);KIR2DS1阳性的NK细胞C1组对靶细胞C2组的杀伤作用高于靶细胞C1及C1/C2组,杀伤率分别为(57.370±1.400)%、(44.190±4.666)%和(36.770±6.560)%(F=11.87,P=0.021);NK细胞抑制性KIR封闭后,其对各组靶细胞的杀伤率更高(F=18.72,P=0.009).结论 NK细胞抑制性KIR封闭后其活性增强,KIR2DS1阳性的NK细胞对靶细胞的杀伤率高于KIR2DS1阴性的NK细胞;NK细胞KIR及HLA-Cw与靶细胞HLA-Cw错配,能够介导KIR2DS1阳性的NK细胞C1组抗原的异源反应性,实现"丢失自我"的识别作用,从而使NK细胞对靶细胞杀伤率增强.

KIR2DS1+ NK cells alloreactivity against HLA-C2 group targets after inhibitory KIR blockades in vitro

Objective To study the killing effects of the killer cell immunoglobutin-like receptors (KIR) KIR2DS1-positive natural killer (NK) cells against acute, myeloid leukemia (AML) target cells, and to explore the KIR, human leucocyte antigen-Cw, and Cw loci (HLA-Cw) of NK cells, and, HLA-Cw of target cells mismatches destruction mechanism. Methods High-purified NK cells separated by DNYAL bead negative selection from healthy donor peripheral blood were taken as effector cells, and the freshly isolated bone marrow mononuclear cells from newly diagnosed AML patients as target cells. The anti-CD158a, CD158b monoclonal antibody was used to block inhibitory KLR receptors of NK cells (such as: KIR2DL1, KIR2DL2, KIR2DL3). The NK cells cytotoxicities against target cells before and after KIR blockades were detected by MTT reduction assay in vitro. Polymerase chain reaction and sequence specific primers (PCR-SSP) genotyping techniques were used to detect HLA-Cw, KIR gene of the healthy donors and patients. NK cells and target cells were divided into group C1 (expressing HLA-Cw 01, 03, 07, 08, 12, 14, 16 alleles), C2 group (expressing HLA-Cw 02, 04, 05, 06, 15, 17, 18 alleles) and the C1/C2 group (co-expressing the alleles in C1 group and C2 group) based on HLA-Cw. Results The purity of NK cells analyzed by flow cytometry was (90.8±6.08)%, and the killing effects of NK cells were significantly enhanced after inhibitory KIR blockades (t=-3.00, P=0.005). The cell lysis in C1 group, KIR2DS1+ NK cells against C2 group target cells (57.37±1.40)% was significantly higher than that against C1 group (44.19±4.67) % and C1/C2 group (36.77±6.56)% target cells (F= 11.87, P = 0.021), furthermore the differences in cell lysis among the above three groups become more evident after the inhibitory KIR blockades (F = 18. 72, P=0. 009). Conclusions The activity of NK cells was increased after the inhibitory KIR blockades, and the killing activities of KIR2DS1+ NK cells were higher than KIR2DS1 NK cells. The incompatibility between KIR, HLA-Cw of NK cells and HLA-Cw of target cells mediated NK alloactivation, realizing "missing self" recognition, and enabling NK cells cytotoxieity against targets.