HBcAg18-27V/I变异体与严重乙型肝炎活动的关系

Relationship between HBcAg18-27V/I epitope variant and severe hepatitis B

目的探讨人白细胞抗原(HLA)-A2限制性细胞毒T淋巴细胞(CTL)表位HBcAg18-27V/I变异体与乙型肝炎活动的关系。方法收集77例严重乙型肝炎活动(SHB)患者和88例慢性乙型肝炎(CHB)患者的血标本,提取其中的HBV DNA,PCR扩增测序HBcAg18-27表位编码区、HBV基因型并鉴定HLA-A2。随访SHB患者至少3个月,在随访时间点留取血标本,提取其中的HBV DNA,PCR扩增测序HBcAg18-27表位编码区,并收集单个核细胞(PBMC)行五聚体染色检测HBcAg18-27表位特异性CD8+记忆T细胞的频数。结果 SHB组HBcAg18-27V的检出率为23.4%(18/77)、CHB组为4.5%(4/88),两组相比,P<0.01。随访存活的10例HBcAg18-27V SHB患者(1例PCR扩展阴性),其中4例HLA-A2阳性患者HBcAg18-27V变异为HBcAg18-27I,而5例HLA-A2阴性者随访后仍检测到HBcAg18-27V。HBcAg18-27V特异性CD8+记忆T细胞的频数高于HBcAg18-27I者。结论在HLA-A2阳性的SHB患者中,发生HBcAg18-27V向HBcAg18-27I表位漂移是HBcAg18-27V诱导的CTL免疫反应的结果;而CTL免疫反应在清除HBcAg18-27V病毒的同时,也参与了HBV相关SHB活动的发生。

Objective To investigate the association between the severity of HBV infection and the vigor of human leukocyte antigen （HLA）-A2 restricted HBcAg18-27V/I specific T-cell response. Methods Seventy-seven patients with severe hepatitis B （SHB） and 88 with chronic hepatitis B （CHB） were involved in the study. HBV genome was isolated from these patients＇serum samples. The HBcAg18-27 encoding region and HBV genotypes were amplified and sequenced by PCR with the HBV genome. The patients with SHB were followed up to 3 months. PBMC of SHB patients were isolated and the pentamer staining was performed to analyze the frequency of HBcAg18-27 epitope-speeific CD8＋ memory cells. Results The prevalence of HBcAg18-27V was found significantly more often in SHB than in CHB [23.4% （18/77） vs 4.5% （4/88）, P 〈0.01]. Ten patients survived primarily infected with pure HBcAg18-27V or the mixture of HBcAg18-27V and HBcAg18-27I were followed up for at least 3 months in SHB group （The sequence of the HBcAg18-27 encoding region could not be amplified in one case）. Among 4 HLA-A2 positive cases, HBcAg18-27V was not detected and it turned into HBcAg18-271. However, HBcAg18-27V could still be detected among 5 HLA-A2 negative cases. The frequency of HBcAg18-27V pentamer specific CDs＋ memory cells was higher than that of HBcAg18-27I pentamer specific CD8 memory cells in case report. Conclusions HBcAg18-27V drifted into the HBcAg18-27I is as a result of HBcAg18-27V epitope-specific CTL response in the HLA-A2 positive SHB patients. Moreover, HBcAg18-27V may be associated with the development of SHB, and the specific CTL response produced by the epitope involves the process of clearing of the prototype virus with HBcAg18-V27.