类风湿关节炎相关多肽对临床诊断的价值

目的 评价利用噬菌体随机肽库,以抗角蛋白抗体(AKA)为配基筛选特异结合的抗原表位的临床诊断价值.方法 将间接荧光法检测AKA阳性的类风湿关节炎(RA)患者混合血清,经33.3%饱和硫酸铵盐析纯化IgG,以此多克隆抗体为配基,对噬荫体递呈的随机12肽库(预先经正常人血清吸收)进行淘筛,将筛选到的阳性噬菌体克隆包被酶标反应板,通过间接ELISA法检测临床RA患者、系统性红斑狼疮(SLE)患者、强直脊柱炎患者及正常人血清标本,评价诊断价值.结果 筛选到一个模拟表位,对RA诊断的特异性为95.6%,敏感性为60%,约臀诊断指数为155.6%,刚性预测值为90%,其氨基酸序列为QSESAGPTFSRR,与人的聚角蛋白微丝蛋白137-148位氨基酸相似.结论 筛选到的多肽QSESAGPTTSRR为RA相关多肽,可能对RA具有一定的特异性诊断价值.

Clinical diagnostic value of potential polypeptides associated with rheumatoid arthritis

Objective To obtain the mimotope recognized by anti-keratin antibody (AKA) by screening a phage random peptide library and evaluate its diagnostic value. Methods IgG was purified from AKA positive pooled serum of rheumatoid arthritis (RA) patients by 33.3% ( NH4)2SO4 ( AKA measured with indirect immunofluorescence). Then the antibody was used as the ligand for biopanning of a 12-mer phage random peptide library. The serum of patients with RA, SLE and normal people were detected with the positive clone by indirect ELISA. Results After 4 rounds of screening, the peptide of mimotope associated with RA was acquired. The diagnostic specificity, positive predictive value and Youden's index were 95.6%, 90% and 155.6% respectively. Its amino acid sequence was QSESAGPTTSRR This sequence was similar to 137-148 amino acid sequence of human filaggrin. Conclusion The RA-associated peptide is acquired by screening a phage random peptide library using polyclonal AKA of RA patients. It may be a specific diagnostic tool of RA.