Clinical Significance of Positive Immunoblotting but Negative Immunofluorescence for Antimitochondrial Antibodies in Patients with Liver Diseases Other than Primary Biliary Cirrhosis
Clinical Significance of Positive Immunoblotting but Negative Immunofluorescence for Antimitochondrial Antibodies in Patients with Liver Diseases Other than Primary Biliary Cirrhosis
复制标题
原发性胆汁性肝硬化以外的肝病患者抗线粒体抗体免疫印迹阳性但免疫荧光阴性的临床意义
作者：
Jun‐ichi Masuda;K. Omagari;H. Miyakawa;H. Hazama;K. Ohba;H. Kinoshita;I. Matsuo;H. Isomoto;I. Murata;S. Kohno
对于除原发性胆汁性肝硬化 (PBC) 之外的其他肝病患者，常规间接免疫荧光法 AMA 呈阴性，可通过免疫印迹法检测抗 2-含氧酸脱氢酶复合物 (2-OADC) 酶（抗线粒体抗体 (AMA) 识别的抗原）的血清反应。目前尚不清楚抗 2-OADC 的存在是否与 PBC 相关或代表此类患者的临床前 PBC。我们通过免疫荧光、免疫印迹和酶抑制试验检测了 59 名除 PBC 之外的肝病患者和 71 名健康受试者的血清样本中 AMA 的免疫反应性。我们还检查了获得阳性结果的患者的临床病程，以阐明这种反应是“真”还是“假”现象。通过间接免疫荧光检测，130 份血清均未呈 AMA 阳性，通过酶抑制测定，未检测到抗丙酮酸脱氢酶复合物 (PDC) 呈阳性。然而，来自健康受试者的 71 份血清中有 7 份 (10%) 含有针对 PDC-E2（四份血清）或支链含氧酸脱氢酶复合物 E2 亚基 (BCOADC-E2)（三份血清）的弱 IgG 类抗体。在来自 PBC 以外的肝病患者的 59 份血清中，通过免疫印迹检测，有 4 份 (7%) 对 2-OADC 产生反应。其中，3份血清来自慢性丙型肝炎病毒（HCV）感染患者，含有针对BCOADC-E2的IgG类自身抗体。通过免疫印迹检测这三名患者的血清对 BCOADC-E2 的反应性在吸收重组 BCOADC-E2 融合蛋白后减弱。在3-5年的随访期间，这三名患者的免疫荧光检测的AMA和酶抑制试验的抗PDC活性始终为阴性。另一份血清来自酒精性肝硬化患者，含有针对E3结合蛋白（E3-BP）的IgM类自身抗体。该患者在接下来的 2 年内没有出现 PBC。我们的结果表明，抗2-OADC抗体可以在PBC以外的一些肝病患者甚至健康个体中检测到。现阶段这些血清反应存在的临床意义尚不清楚，但抗 BCOADC-E2 的产生可能与某些患者中 HCV 的存在有关。对更大人群的进一步前瞻性研究应阐明抗 2-OADC 反应是否可以先于 PBC 的临床发展。
The serum reaction to anti-2-oxo-acid dehydrogenase complex (2-OADC) enzymes, the antigens recognized by antimitochondrial antibodies (AMA), can be detected by immunoblotting in patients with liver diseases other than primary biliary cirrhosis (PBC), who are negative for AMA by conventional indirect immunofluorescence. Whether the presence of anti-2-OADC is related to PBC or represents preclinical PBC in such patients is obscure at present. We examined the immunoreactivity of AMA by immunofluorescense, immunoblotting, and enzyme inhibition assay in serum samples from 59 patients with liver diseases other than PBC and 71 healthy subjects. We also examined the clinical course of the patients in whom a positive result was obtained to elucidate whether such reaction was a "true" or "false" phenomenon. None of the 130 sera was positive for AMA by indirect immunofluorescence or for anti-pyruvate dehydrogenase complex (PDC) by enzyme inhibition assay. However, seven of 71 (10%) sera from healthy subjects contained weak IgG class antibody to PDC-E2 (four sera) or E2 subunit of branched-chain oxo-acid dehydrogenase complex (BCOADC-E2) (three sera). Of the 59 sera from patients with liver diseases other than PBC, four (7%) reacted against 2-OADC by immunoblotting. Of these, three sera were from patients with chronic hepatitis C virus (HCV) infection, and contained IgG class autoantibody to BCOADC-E2. The serum reactivity to BCOADC-E2 detected by immunoblotting in these three patients diminished after absorption with recombinant BCOADC-E2 fusion protein. During the 3-5 year follow-up period, AMA by immunofluorescence and anti-PDC activity by enzyme inhibition assay were always negative in these three patients. The other one serum was from patient with alcoholic cirrhosis, and contained IgM class autoantibody to E3 binding protein (E3-BP). This patient did not develop PBC during the following 2 years. Our results showed that anti-2-OADC antibodies could be detected in some patients with liver diseases other than PBC, and even in healthy individuals. The clinical significance of the presence of these serum reactions is obscure at this stage, but the production of anti-BCOADC-E2 may be linked to the presence of HCV in certain patients, Further prospective studies of larger population should clarify whether anti-2-OADC reaction can precede the clinical development of PBC.