Increased levels of BPI-ANCA in patients with primary Sjögren’s syndrome are associated with lung involvement

The goal of this study was to investigate the association between bactericidal permeability increasing (BPI)-antineutrophil cytoplasmic antibody (ANCA) protein levels and primary Sjogren's syndrome (pSS) with lung involvement, as well as the potential diagnostic performance of BPI-ANCA. The levels of BPI-ANCA in pSS patients with (n = 36) and without (n = 85) lung involvement were measured using a commercial ELISA kit. Serological biomarkers and cytokines were measured in these patients as well. Lung involvement was determined by high-resolution computed tomography (HRCT) and/or clinical symptoms. The diagnostic performance of lung involvement was determined by receiver operating characteristic (ROC) curves. The percentage of neutrophils (NEUT%), neutrophil–lymphocyte ratio (NLR), erythrocyte sedimentation rate (ESR), and the levels of BPI-ANCA, C-reactive protein (CRP), interleukin-2 (IL-2) and IL-6 exhibited an upward trend, while the percentage of lymphocytes (LYMP%) and albumin (ALB) level exhibited a downward trend in the lung involvement group. The combination of BPI-ANCA, NEUT% and ALB significantly increased the area under the ROC curve (AUC) to 0.837 (95% confidence interval: 0.742–0.907, sensitivity: 82.14%, specificity: 81.36%, P