自身免疫性肝炎患者中可溶性肝抗原B细胞抗原表位分布特征分析

The feature analysis of soluble liver antigen B cell epitopes distribution in autoimmune hepatitis patients

目的分析自身免疫性肝炎（AIH）患者中可溶性肝抗原（SLA）B细胞抗原表位分布特征。方法以21例AIH患者为研究对象，以15例原发性胆汁性肝硬化（primary biliary cirrhosis，PBC）患者、20例慢性病毒性肝炎患者、20例健康体检者为对照组。采用人工合成肽段与ELISA方法，检测sLA抗原的B细胞抗原表位，并与T细胞识别片段及SLA进化过程中的序列布进行对比。结果21例AIH患者中，10例患者血清与SLA抗原肽库呈现阳性反应，阳性率为47．62％，10例阳性反应血清与SLA连续一维肽库反应的A值以肽库7（aa385～441）反应最强，均值为0．400～0．109，明显高于其他各组肽库A值（P〈0．001），其是高度保守蛋白的不保守区域。T细胞识别的区域与B细胞识别的区域有所不同，主要位于肽库1及肽库2，反应频率分别为30％、40％，对肽库7的反应频率为10％。结论SLAB细胞线性抗原表位位于aa385～441，具有高度的一致性，并与T细胞识别的部位有交叉重叠现象，提示在AIH发病机制中存在细胞免疫与体液免疫的多重、相互关联的机制作用。

Objective To analyze the feature of B cell epitope of soluble liver antigen（SLA） in autoimmune hepatitis. Methods Twenty-one autoimmune hepatitis （AIH） were enrolled the study. The control groups included 15 primary biliary cirrhosis（PBC） patients, 20 chronic virus hepatitis patients and 20 heaths. The serum incubated with coated one dimension of SLA peptide pools by ELISA for mapping the B cell epitopes. ELISPOT was performed to screen the SLA specific T cell response by observing the secre- tion of IFN-γ after PBMC simulated. Results Ten serum samples from AIH patients recognized the SLA peptide pools, the frequency was 47.62%, which was higher than PBC group, virus hepatitis group and nor- mal control group, P value was 0.001, 〈0.001 and 〈0.001, respectively. The 10 positive serum dominant response to SLA 7 th pool（ aa385-441 ）, which laid in the unique no conservative region of the SLA molecular. T cell recognizing regions laid dominantly in first and second pool, the frequency was 30% and 40%, respectively, however the recognized frequency of 7th pool was 10%. Conclusion B cell linear epitopes lie in the sequence aa385-441, which is the unique unconservative region in the high conservative SLA molecu- lar and overlaps with part sequence of T cell epitopes. The results show it is complex and interaction that SLA induced humoral-mediated immunity and cellular immunity to involve in AIH pathogenesis.