Anti-neutrophil cytoplasmic autoantibodies against bactericidal/permeability-increasing protein in patients with rheumatoid arthritis and their correlation with bronchial involvement.

Anti-neutrophil cytoplasmic autoantibodies against bactericidal/permeability-increasing protein (BPI-ANCA) are known to be present in patients with cystic fibrosis, diffuse panbronchiolitis, and inflammatory bowel disease, especially in relation to chronic Gram-negative bacterial infection. To investigate the possible role of BPI-ANCA in rheumatoid arthritis (RA), we measured the serum titer of BPI-ANCA and examined clinical manifestations, including pulmonary complications, in patients with RA. Seventy-four RA patients were recruited to our study. The titer of BPI-ANCA was measured by enzyme-linked immunosorbent assay (ELISA). Pulmonary complications were evaluated using high-resolution computed tomography (HRCT), which revealed 26 patients with bronchial diseases (BD group), 25 with interstitial pneumonia (IP group), and 23 without any particular lung lesion (normal group). The correlations between the titer of BPI-ANCA and patients' clinical and laboratory findings were then analyzed. The numbers of tender joints, swollen joints, and the Disease Activity Score including 28 joint count were significantly higher in the BD group. The titer of BPI-ANCA was positively correlated with age, erythrocyte sedimentation rate (ESR), and bronchial involvement in all subjects. Stepwise multiple regression analysis of factors affecting the titer of BPI-ANCA selected ESR and bronchial involvement as independent variables. Our results show that BPI-ANCA was positively correlated with chronic inflammatory status in RA patients, and we is believe it is positively linked with bronchial diseases.