Serum IgG ACPA-IgM RF immune complexes were detected in rheumatoid arthritis patients positive for IgM ACPA.
Serum IgG ACPA-IgM RF immune complexes were detected in rheumatoid arthritis patients positive for IgM ACPA.
复制标题
DOI：
--
复制
发表时间：
2018-07
影响因子：
3.7
通讯作者：
A. Haraguchi;H. Yamada;M. Kondo;K. Okazaki;J. Fukushi;A. Oyamada;Y. Yoshikai;Y. Nakashima
中科院分区：
文献类型：
--
作者：
A. Haraguchi;H. Yamada;M. Kondo;K. Okazaki;J. Fukushi;A. Oyamada;Y. Yoshikai;Y. Nakashima
由于IgM抗体的存在是持续免疫应答的标志，我们旨在通过检测IgM抗瓜氨酸蛋白抗体（ACPA）水平来识别免疫活性类风湿关节炎（RA）患者。方法采用酶联免疫吸附试验（ELISA）检测176例RA患者血清中IgM型ACPA水平，比较其与瓜氨酸肽和非瓜氨酸肽的反应性，以确定特异性。IgM类风湿因子（RF）对IgM ACPA检测的影响通过使用蛋白G缀合珠去除IgG或使用瓜氨酸化肽缀合珠纯化ACPA来检查。结果虽然在一些患者（11%）中检测到瓜氨酸化蛋白特异性IgM，但在大量患者样本（12%）中检测到瓜氨酸化和非瓜氨酸化肽反应性IgM分子。IgM ACPA阳性反应与IgG ACPA和IgM RF的存在相关。令人惊讶的是，蛋白G介导的IgG从血清中的去除消除了IgM ACPA的阳性，表明IgG ACPA-IgM RF复合物被检测到。通过检测蛋白G珠粒和瓜氨酸化肽缀合珠粒中的IgM RF证实了这一假设。结论：在尝试检测IgM ACPA时，我们发现大多数假阳性反应是由于存在IgM分子（对瓜氨酸化蛋白没有特异性）和IgG ACPA-IgM RF免疫复合物。后一种复合物已被提出在RA的发病机制中发挥作用，在这里，我们第一次证明了它在RA患者血清中的存在。
OBJECTIVES Since the presence of IgM antibodies is a hallmark of ongoing immune response, we aimed to identify immunologically active rheumatoid arthritis (RA) patients by detecting IgM anti-citrullinated protein antibody (ACPA) levels. METHODS IgM ACPA levels were determined in the serum of 176 RA patients by enzyme-linked immunosorbent assay, in which parameters of reactivity against citrullinated and non-citrullinated peptides were compared to ensure the specificity. Influence of IgM rheumatoid factor (RF) on IgM ACPA detection was examined by removing IgG, using protein G-conjugated beads, or by purifying ACPA, using citrullinated peptide-conjugated beads. RESULTS Although IgM specific for citrullinated proteins was detected in some patients (11%), IgM molecules reactive to both citrullinated and non-citrullinated peptides were detected in a substantial number of patient samples (12%). IgM ACPA-positive reactions were associated with the presence of IgG ACPA and IgM RF. Surprisingly, protein G-mediated removal of IgG from the serum eliminated positivity for IgM ACPA, suggesting that IgG ACPA-IgM RF complex was being detected. This assumption was confirmed by the detection of IgM RF in the eluate of protein G beads and citrullinated peptide-conjugated beads. CONCLUSIONS In an attempt to detect IgM ACPA, we mostly revealed false positive reactions due to the presence of IgM molecules, which were not specific for citrullinated proteins, and IgG ACPA-IgM RF immune complex. The latter complex had been proposed to play a role in the pathogenesis of RA, and here, for the first time, we have demonstrated its presence in the sera of RA patients.