人内质网分子伴侣BiP抗原表位筛选及其在RA血清学诊断中的作用研究

Screen for antigenic peptides of BiP and its application in diagnosis for rheumatoid arthritis

目的:筛选鉴定人内质网分子伴侣BiP抗原表位多肽,探讨其在类风湿性关节炎(Rheumatoid arthritis,RA)血清学诊断中的价值。方法:运用计算机软件分析BiP蛋白的结构特点及抗原决定簇分布,根据结果设计合成系列多肽。比较合成多肽与RA患者血清(BiP抗体阳性)IgG的反应强弱,鉴定抗原抗体反应最强的抗原表位多肽。进一步以获得的BiP抗原表位多肽作为包被抗原,检测79例RA患者、34例系统性红斑狼疮(SLE)患者、66例干燥综合征(SS)患者和173例正常人血清中抗BiP抗原表位多肽IgG抗体水平。结果:筛选到一条与RA患者血清反应最强的多肽(N403),抗N403多肽IgG抗体在RA患者中的阳性率(67%),明显高于SS患者(29%)、SLE患者(0%)、和正常人(0%)(P<0.01)。抗N403多肽IgG抗体在RA血清学诊断中的敏感性为67%,特异性为93%。而且该抗体的检测对于RF、CCP、HRF、RA33、AKA、APF等抗体阴性的RA患者的诊断具有重要意义。结论:筛选获得的BiP抗原表位多肽N403,其检测抗体在RA临床血清诊断中具有很好的应用价值。

Objective：To screen and identify the antigenic determinants of human stress protein BiP （immunoglobulin binding protein） and to investigate the sensitivity and specificity of BiP antigenic peptides in the diagnosis of rheumatoid arthritis （RA）. Methods： Based on the structure and predicted antigenic epitope sites of BiP protein, three peptides derived from BiP protein were synthesized. The recombinant BiP protein and the three synthesized peptides were subjected to screening with RA patient sera. The peptide with the strongest immunoreactivity was used as antigenic peptide to detect anti-BiP-peptide antibodies in the sera of 79 patients with RA, 34 patients with systemic lupus erythematosus （SLE）, 66 patients with Sjogren＇s syndrome （SS） and 173 normal controls. Results： The N-terminal peptide of amino acids 403 to 416 （N403） was the epitope of BiP protein. The prevalence of anti-N403 peptide antibodies in patients with RA, SS, SEE, and normal controls were 67 %, 29 %, 0%,0%, and the sensitivity and specificity of the autoantibodies in RA were 67 % and 93 %, respectively. Conmbined with our previous statistical results, antibodies against N403 peptide could be used for RA diagnosis in RA patients who were in the negative groups of RF, CCP, HRF, RA33, AKA and APF antibodies. Conclusion： These results suggest that the anti-BiP-N403 peptide antibody is of great value in the diagnosis of RA which is showed with highest sensitivity and specificity to RA patient than to other controls.