ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES (ANCA) DIRECTED AGAINST BACTERICIDAL PERMEABILITY-INCREASING PROTEIN (BPI) - A NEW SEROMARKER FOR INFLAMMATORY BOWEL-DISEASE AND ASSOCIATED DISORDERS

It was our purpose to determine the immunodiagnostic value of ANCA dir ected against BPI in diseases known to be associated with ANCA, such a s ANCA-associated vasculitides, inflammatory bowel disease (IBD) and t he associated condition primary sclerosing cholangitis. The immunoreac tivity of recombinant BPI (rBPI) was established in order to develop a n ELISA specific for rBPI. By means of this assay, BPI-ANCA were asses sed in sera of 178 patients with IBD or the associated disorder primar y sclerosing cholangitis, 112 patients with ANCA-associated vasculitid es, and in sera of 182 disease and 140 healthy controls. BPI-ANCA were found to be closely associated with IBD and primary sclerosing cholan gitis (34% and 44% of ANCA-positive sera, respectively). By contrast, BPI-ANCA positivity was low (<10%) in the double-negative sera of pati ents with ANCA-associated vasculitides and in disease and healthy cont rols. BPI-ANCA appear to constitute an important marker for IBD and pr imary sclerosing cholangitis, but not for the ANCA-associated vasculit ides.