Interstitial lung diseases (ILD) are a heterogeneous group of illnesses of known and unknown aetiology. Differential diagnosis among the three disorders is often challenging. Specific biomarkers with good sensitivity and specificity are therefore needed to predict clinical outcome and guide clinical decisions. The aim of this study was to investigate inflammatory/fibrotic biomarkers, to determine whether single mediators or panels of mediators could be useful to stratify patients into three distinct domains: sarcoidosis, idiopathic pulmonary fibrosis (IPF) and chronic hypersensitivity pneumonitis (cHP). A total of 163 ILD patients monitored at Siena Referral Centre for Sarcoidosis and other Interstitial Lung Diseases were enrolled in the study. Clinical data, pulmonary function tests and biochemical analytes were retrospectively collected. SAA levels were detected by ELISA kit and Krebs von den Lungen 6 (KL-6) were measured by CLEIA method, for sarcoidosis, cHP and IPF patients. Multiple comparison analysis showed significant differences in C reactive protein (CRP), white blood cell count (WBC) and creatinine levels between the three groups. In the logistic regression model, KL-6, CRP and WBC showed areas under curves (AUC) 0.86, for sarcoidosis diagnosis. The logistic regression model KL-6 and SAA showed the best performance with an AUC 0.81 for discriminating IPF than cHP and sarcoidosis. For differential diagnosis of IPF and cHP, KL-6 and SAA were considered in the logistic regression model, showed an AUC 0.79. The combination of serum biomarkers proposed here offers insights into the pathobiology of ILDs. These panels of bioindicators will improve diagnostic accuracy and will be useful in the clinical management of ILDs.

间质性肺病 (ILD) 是一组具有已知和未知病因的异质性疾病。三种疾病之间的鉴别诊断通常具有挑战性。因此，需要具有良好敏感性和特异性的特定生物标志物来预测临床结果和指导临床决策。本研究的目的是调查炎症/纤维化生物标志物，以确定单一介质或介质组是否可用于将患者分为三个不同的领域：结节病、特发性肺纤维化 (IPF) 和慢性过敏性肺炎 (cHP)。在锡耶纳结节病和其他间质性肺疾病转诊中心监测的总共 163 名 ILD 患者参加了该研究。回顾性收集临床数据、肺功能测试和生化分析物。对于结节病、cHP和IPF患者，通过ELISA试剂盒检测SAA水平，通过CLEIA方法测量Krebs von den Lungen 6 (KL-6)。多重比较分析显示三组之间C反应蛋白（CRP）、白细胞计数（WBC）和肌酐水平存在显着差异。在逻辑回归模型中，KL-6、CRP 和 WBC 的曲线下面积 (AUC) 为 0.86，用于诊断结节病。Logistic 回归模型 KL-6 和 SAA 在区分 IPF 方面表现出最佳性能，AUC 为 0.81，而不是 cHP 和结节病。对于 IPF 和 cHP 的鉴别诊断，在逻辑回归模型中考虑了 KL-6 和 SAA，显示 AUC 为 0.79。这里提出的血清生物标志物的组合提供了对 ILD 病理生物学的见解。