Anti-BPI autoantibodies have been peculiar for a number of reasons, most notably their strong linkage with patients suffering from various diseases, particularly cystic fibrosis (CF) [10,75,76] and bronchiectasis [6,67], but also including inflammatory bowel diseases (IBD) [63,77,78], vasculitis [63,67,68,79], reactive arthritis [80], necrotizing and crescentic glomerulonephritis [81], and primary sclerosing cholangitis [82,83]. Here, BPI is linked to inflammatory bowel disease.