Villalta Danilo, Bizzaro Nicola, Da Re Mirella, Tozzoli Renato, Komorowski Lars, Tonutti Elio
Allergologia e Immunologia Clinica, Pordenone, Italy.
Autoimmunity. 2008 Feb;41(1):105-10. doi: 10.1080/08916930701619896.
Smooth muscle antibodies (SMA) with anti-F-actin specificity are commonly regarded as specific markers of type 1 autoimmune hepatitis (AIH-1) but, at the moment, a gold standard method for their identification is not available.
To evaluate the diagnostic accuracy for AIH-1 of three new methods of detecting anti-F-actin antibodies, and to compare the results with those obtained using the indirect immunofluorescence (IIF) method on rodent tissue.
The sera of 33 AIH-1 patients and 104 controls (eight with type 2 AIH, 30 with chronic hepatitis C, 16 with celiac disease, 40 with primary biliary cirrhosis, and 10 with liver steatosis) were assayed for anti-F-actin antibodies using four methods: two IIF methods (one on rat tissue sections and the other on VSM 47 cell line derived from the thoracic aorta of rat embryo), an ELISA method and an Immunodot (ID) method.
The diagnostic sensitivity, specificity, positive predictive value and negative predictive value were, respectively, 51.5, 95.2, 77.3 and 86.1% for IIF on the VSM 47 cell line; 63.6, 86.5, 60 and 88.2% for the ELISA method; 72.7, 82.7, 57.1 and 90.5% for the ID assay; and 57.6, 96.1, 82.6 and 87.7% for the IIF on rat tissue sections.
The methods used for anti-F-actin antibody detection have different diagnostic performances. Both IIF methods, the one on rat tissues and the other on VSM47 cell line, are highly specific for AIH-1. In contrast, ELISA and especially ID show positive results in control population, although usually at low levels (with the single exception of PBC patients). Therefore, having a high positive predictive value, both IIF methods are reliable tools for the specific detection of AIH-associated anti-F-actin autoantibodies, whereas the immunometric assays might be integrated into the diagnostic scheme as second level tests upon improvement of their respective cut-offs to confirm anti-F-actin positivity in case of SMA positivity.
具有抗F-肌动蛋白特异性的平滑肌抗体（SMA）通常被视为1型自身免疫性肝炎（AIH-1）的特异性标志物，但目前尚无用于鉴定它们的金标准方法。
评估三种检测抗F-肌动蛋白抗体新方法对AIH-1的诊断准确性，并将结果与使用啮齿动物组织间接免疫荧光（IIF）法获得的结果进行比较。
使用四种方法检测33例AIH-1患者和104例对照（8例2型AIH、30例慢性丙型肝炎、16例乳糜泻、40例原发性胆汁性肝硬化和10例肝脂肪变性）血清中的抗F-肌动蛋白抗体：两种IIF方法（一种在大鼠组织切片上，另一种在源自大鼠胚胎胸主动脉的VSM 47细胞系上）、一种ELISA方法和一种免疫斑点（ID）方法。
VSM 47细胞系上IIF的诊断敏感性、特异性、阳性预测值和阴性预测值分别为51.5%、95.2%、77.3%和86.1%；ELISA方法分别为63.6%、86.5%、60%和88.2%；ID检测分别为72.7%、82.7%、57.1%和90.5%；大鼠组织切片上IIF分别为57.6%、96.1%、82.6%和87.7%。
用于检测抗F-肌动蛋白抗体的方法具有不同的诊断性能。两种IIF方法，一种在大鼠组织上，另一种在VSM47细胞系上，对AIH-1具有高度特异性。相比之下，ELISA尤其是ID在对照人群中显示出阳性结果，尽管通常水平较低（原发性胆汁性肝硬化患者除外）。因此，两种IIF方法具有较高的阳性预测值，是特异性检测AIH相关抗F-肌动蛋白自身抗体的可靠工具，而免疫测定法在提高各自的临界值后，可作为二级检测纳入诊断方案，以在SMA阳性时确认抗F-肌动蛋白阳性。
