类风湿关节炎相关多肽对临床诊断的价值

Clinical diagnostic value of potential polypeptides associated with rheumatoid arthritis

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，对噬菌体递呈的随机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％，约登诊断指数为155．6％，阳性预测值为90％，其氨基酸序列为QSESAGPTTSRR，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。

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-met 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.