青少年慢性乙型肝炎患者乙型肝炎病毒特异性CD8＋T淋巴细胞程序性死亡分子-1的表达

PD-1 expression in HlcAg-specitic CD8＋ T cells of adolescents with chronic HBV infection

目的探计巨性HBV感染青少年患者免疫耐受期与免疫清除期外周血HBcAg18-27讲表位特异性CD8＋T淋巴细胞程序性死亡分子－1（PD-1）的表达I青况，探讨PD-1与HBV感染免疫状态的关系。方法选择105例HBV青少年感染者，全部病例行肝活组织检查，其中免疫清除期55例、免疫耐受期50例，同时选择15例健康青年为正常对照组。流式细胞术检测外周血单个核细胞（PBMC）及70例HLA-A2阳性患者HBcAgl8-27表位特异性CD8＋T淋巴细胞上PD-1表达水平，RT-PCR法检测所有受试者外周血PBMC中PD-1mRNA的表达。两组间均数差异采用两独立样本的t检验，多组间均数比较采用单因素方差分析，相关性分析采用Pearson相关分析。结果免疫清除期患者外周血HBcAg，＋凹表位特异性CD8＋T淋巴细胞阳性率（46．39％±4．10％）明显高于免疫耐受期（31．82％±4．01％），两组比较，t=18．08，P〈0．01，差异有统计学意义。而HBcAgIB-27特异性CD8＋T淋巴细胞PD-1阳性表达率（40．600／0±11．30％）明显低于免疫耐受期（56．39％±13．69％），两组比较，t=4．72，P〈0．01，差异有统计学意义。相关分析显示HBcAgm，特异性CD8＋T淋巴细胞阳性率与PI）-1表达频率呈负相关（r=-0．463，P〈0．01），与HBVDNA血清水平成正相关（r=0．882，P〈0．01），与肝组织炎症积分呈负相关（r=-0．76，P〈0．01）。免疫耐受组阳MC中PD-1mRNA的表达（1．08土0．03）高于免疫清除组（0．924-0．03），两组比较，t=30．89，P〈0．01，差异有统计学意义。结论Pn-1的高表达抑制HBV特异陛CD8＋T淋巴细胞活化可能是导致慢性HBV感染青少年患者的免疫耐受机制。

Objective To investigate the differential expression of programmed death-1 （PD-1） in the hepatitis B core antigen （HBcAg）17-28-specific CD8＋ T cell subsets of adolescent patients with chronic hepatitis B virus （HBV） infection during the immune tolerant phase and the immune clearance phase. Methods A total of 105 patients between the ages of 12-28 years old （mean age 17.20 ＋ 6.35） with chronic HBV infection and 15 healthy age-matched individuals were enrolled in the study. The patients were divided into two groups according to their current status in immune clearance phase 07 = 55） or immune tolerant phase 07 = 50）, as determined by hepatic biopsy pathology. Flow cytometry was used to detect HLA-A2 type and PD-1 expression on peripheral blood mononuclear cells （PBMC） and HBcAg17.28-specific CD8＋ T cells. PD-1 mRNA levels in PBMCs were measured by reverse transcription-polymerase chain reaction （RT-PCR）. Independent samples t-test was used to compare means between the two groups, and one-way ANOVA was used to compare means among multiple groups. Pearson＇s correlation coefficient was used to assess the significance of correlation.Results The frequency of HBcAgls.27-specific CD8＋ T cells was significantly higher in the immune clearance phase group than in the immune tolerant phase group （t= 18.08,P 〈 0.01）, but the expression of PD-1 on the HBcAg18-27 specific CD8＋ T cells was significantly lower in the immune clearance phase group than in the immune tolerant phase group （t = 4.72, P 〈 0.01）. A negative correlation existed between the frequency of HBcAg18-27-specific CD8＋ T cells and PD-1 expression （r = -0.463, P 〈 0.01）. A positive correlation existed between HBV viral load and PD-1 expression on the HBcAgls.27-specific CD8＋ T cells in chronic HBV infection patients （1＂ = 0.882, P 〈 0.01）, and there was a negative correlation between PD-1 expression levels on HBcAgls.27-specific CD8＋ T ceils and hepatic tissue inflammation score （r = -0.76, P 〈 0.01）. PD-1 mRNA in PBMCs was significantly higher in the immune tolerant phase group than in the immune clearance phase group （t = 30.89, P 〈 0.01）. Conclusion Up-regulated expression of PD-1 is associated with HBV-specific CD8＋ T cells and may play a crucial role in inhibiting their function during the immune tolerance phase of chronic HBV infection in adolescents.