乙型肝炎病毒核心区基因变异与细胞免疫

目的 探讨慢性乙型肝炎患者乙型肝炎病毒(HBV)核心区Leu60Val变异与机体细胞免疫水平的关系。方法 通过流式细胞分析技术(FCM)检测外周血T淋巴细胞亚群,利用酶联免疫吸附试验(ELISA)检测血清细胞因子[干扰素γ(IFN-γ)、肿瘤坏死因子α(TNF-α)和白细胞介素2(IL-2)]水平,采用聚合酶链反应(PCR)扩增HBV DNA C基因区片段,并对PCR产物直接测序。结果 91例慢性乙型肝炎患者发生Leu60Val变异者19例,变异率为20.9％,随病情加重变异率逐渐增加,以重型肝炎组最高;Val60变异株组IFN-γ、TNF-α水平明显增高(t值分别为2.584、4.766,P<0.01),CD_4~1/CD_8~1比值逐渐升高(t=2.275,P<0.05)。结论 Val60变异株可能通过增加与Ⅰ类人白细胞抗原(HLA-Ⅰ)的亲和力,或上调HLA-Ⅰ类分子的表达,从而激活大量的细胞毒性T淋巴细胞释放细胞因子,并同时在肝脏局部发挥免疫效应,提高对宿主的杀伤力。

Relationship between the HBV core gene mutation and the cellular immunity in host

OBJECTIVES: To study the relationship between the mutation of Leu60Val in HBV core region and the cellular immunity in patients with chronic hepatitis B (CHB). METHODS: HBV DNA C gene mutation was confirmed by polymerase chain reaction (PCR) and sequencing the products directly. The cytokines (IFN-gamma, TNF-alpha and IL-2) levels in serum were measured by enzyme linked immunosorbent assay (ELISA). The distribution of T-lymphocyte subpopulations in peripheral blood was detected by flow cytometry (FCM). RESULTS: The mutation of Leu60Val was found in 19 out of the 91 CHB patients. With the CHB severity, the mutation rate was getting higher, especially in the severe hepatitis group. The IFN-gamma and TNF-alpha levels were much higher in mutant strain group than those in wild strain group (t=2.584, 4.766, P<0.01), so was the ratio of CD4+/CD8+ (t=2.275, P<0.05). CONCLUSION: The mutant strain of 60Val may increase affinity to HLA-I molecule, or up-regulate the expression of HLA-I molecule, resulting in the activation of CTL to release the cytokines and cause immune response in liver.