Autoantibodies are a hallmark feature of Connective Tissue Diseases (CTD). Their presence in patients with idiopathic interstitial lung disease (ILD) may suggest covert CTD. We aimed to determine the prevalence of CTD autoantibodies in patients diagnosed with idiopathic ILD. 499 patient sera were analysed: 251 idiopathic pulmonary fibrosis (IPF), 206 idiopathic non-specific interstitial pneumonia (iNSIP) and 42 cryptogenic organising pneumonia (COP). Autoantibody status was determined by immunoprecipitation. 2.4% of IPF sera had a CTD-autoantibody compared to 10.2% of iNSIP and 7.3% of COP. 45% of autoantibodies were anti-synthetases. A novel autoantibody targeting an unknown 56 kDa protein was found in seven IPF patients (2.8%) and two NSIP (1%) patients. This was characterised as anti-annexin A11. Specific guidance on autoantibody testing and interpretation in patients with ILD could improve diagnostic accuracy. Further work is required to determine the clinical significance of anti-annexin A11.

中文翻译：

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“特发性”间质性肺病患者结缔组织病自身抗体和新型自身抗体抗膜联蛋白 A11 的鉴定

自身抗体是结缔组织病 (CTD) 的一个标志性特征。它们在特发性间质性肺病 (ILD) 患者中的存在可能提示隐性 CTD。我们的目的是确定诊断为特发性 ILD 的患者中 CTD 自身抗体的患病率。对 499 名患者血清进行了分析：251 名特发性肺纤维化 (IPF)、206 名特发性非特异性间质性肺炎 (iNSIP) 和 42 名隐源性机化性肺炎 (COP)。通过免疫沉淀测定自身抗体状态。 2.4% 的 IPF 血清含有 CTD 自身抗体，而 iNSIP 的这一比例为 10.2%，COP 的比例为 7.3%。 45% 的自身抗体是抗合成酶。在七名 IPF 患者 (2.8%) 和两名 NSIP (1%) 患者中发现了一种针对未知 56 kDa 蛋白质的新型自身抗体。其特征为抗膜联蛋白 A11。对 ILD 患者自身抗体检测和解释的具体指导可以提高诊断准确性。需要进一步的工作来确定抗膜联蛋白 A11 的临床意义。