These ANCA directed against BPI proteins (BPI-ANCA) have been identified in several inflammatory disorders and infectious diseases, such as inflammatory bowel diseases (IBD), chronic obstructive pulmonary disease (COPD), non-cystic fibrosis (CF) bronchiectasis, tuberculosis, and cystic fibrosis associated with Pseudomonas aeruginosa (P. aeruginosa) infection. Here, BPI is linked to inflammatory bowel disease.