Objective: To investigate the changes of subpopulation and function of natural killer (NK) cells in adult patients with infectious mononucleosis related liver injury.
Methods: Seventeen healthy controls, twenty-six patients of infectious mononucleosis (IM) without liver injury, and twenty-one IM patients with liver injury were enrolled in this study. Peripheral blood was collected. Plasma and peripheral blood mononuclear cells (PBMC) were purified. Plasma interleukin-15 (IL-15) level was measured by enzyme linked immunosorbent assay. Three NK cell subpopulations, including CD56+CD16-, CD56+CD16+, and CD56-CD16+ NK cells, were assessed by flow cytometry. PBMC were co-cultured with 721.221, K562, and P815-Ab cells, respectively. CD107a expression and CD16 mean fluorescence intensity (MFI) in NK cells was investigated by flow cytometry. PBMC from IM patients with liver injury were stimulated with anti-IL-15 neutralizing antibody, and the change of NK cell function was observed. One-way ANOVA and paired t test were used for statistical analysis.
Results: The percentage of CD56+CD16- NK cells in IM patients with liver injury (7.36±0.92)% and IM patients without liver injury (10.67±1.37)% were lower than that of controls (12.02±2.51)% (P<0.05). CD56+CD16- NK cell frequency in IM patients with liver injury also was lower than that in IM patients with liver injury (P<0.0001). The percentage of CD56+CD16+ NK cells in IM patients with liver injury (62.03±8.78)% and IM patients without liver injury (44.74±13.03)% were higher than that in controls (40.74±10.15)% (P<0.05). CD56+CD16+ NK cell frequency in IM patients with liver injury also was higher than that in IM patients with liver injury (P<0.0001). There was no statistical difference of CD56-CD16+ NK cell proportion among three groups (P=0.427). Plasma IL-15 level in IM patients with liver injury (309.1±68.00) pg/ml were higher than that in IM patients without liver injury (269.6±53.57) pg/ml and controls (257.4±73.93) pg/ml (P<0.05). NK cells induced target cell death through different receptors upon activation, the ratio of CD107a-positive cells in NK cells of IM patients with liver injury was higher than that in IM patients without liver injury and controls (P<0.05), while CD16 MFI in NK cells in IM patients with liver injury was lower than that in IM patients without liver injury and controls (P<0.05). The percentage of CD107a positive cells in NK cells was significantly reduced in response to anti-IL-15 neutralizing antibody stimulation in IM patients with liver injury (P<0.05).
Conclusion: IM patients with liver injury presented imbalance of NK cell subpopulation and enhanced NK cell function. The elevation of IL-15 might contribute to promote NK cell cytotoxicity in IM patients with liver injury.
题目: 成人传染性单核细胞增多症相关肝损伤患者自然杀伤 细胞亚群的比例和功能变化.
目的: 分析成人传染性单核细胞增多症（IM）相关肝损伤患者自然杀伤（NK）细胞亚群比例和功能的变化.
方法: 入组17例健康对照者、26例传染性单核细胞增多症无肝损伤患者、21例IM合并肝损伤患者，采集外周血，分离血浆和外周血单个核细胞（PBMC），酶联免疫吸附试验检测血浆白细胞介素-15（IL-15）水平，流式细胞术检测CD56+CD16-、CD56+CD16+、CD56-CD16+ 3个NK细胞亚群比例。PBMC分别与721.221细胞、K562细胞、P815-Ab细胞共培养，流式细胞术检测NK细胞中CD107a的表达和CD16平均荧光强度（MFI）。使用抗IL-15中和抗体刺激IM合并肝损伤患者PBMC，观察NK细胞功能变化。组间比较采用单因素方差分析或配对t检验.
结果: CD56+CD16-NK细胞在IM合并肝损伤组（7.36±0.92）%和IM无肝损伤组（10.67±1.37）%的比例均明显低于对照组（12.02±2.51）%（P<0.05），IM合并肝损伤组CD56+CD16-NK细胞比例低于IM无肝损伤组（P<0.0001）。CD56+CD16+NK细胞在IM合并肝损伤组（62.03±8.78）%和IM无肝损伤组（44.74±13.03）%的比例高于对照组（40.74±10.15）%（P<0.05），IM合并肝损伤组CD56+CD16+NK细胞比例高于IM无肝损伤组（P<0.0001）。CD56-CD16+NK细胞比例在3组之间的差异无统计学意义（P=0.427）。血浆IL-15在IM合并肝损伤组（309.1±68.00）pg/ml的水平明显高于IM无肝损伤组（269.6±53.57）pg/ml和对照组（257.4±73.93）pg/ml（P<0.05）。NK细胞通过不同受体介导杀伤相应靶细胞后，IM合并肝损伤组NK细胞中CD107a阳性细胞比例明显高于IM无肝损伤组和对照组（P<0.05），CD16 MFI明显低于IM无肝损伤组和对照组（P<0.05）。抗IL-15中和抗体刺激IM合并肝损伤患者PBMC后，NK细胞中CD107a比例明显降低（P<0.05）.
结论: IM合并肝损伤患者中存在NK细胞亚群失衡和功能增强，IM合并肝损伤患者中IL-15水平升高可能增强NK细胞的毒性作用.
Keywords: Epstein-Barr virus; infectious mononucleosis; liver injury; natural killer cells.