ANTINEUTROPHIL CYTOPLASM AUTOANTIBODIES AGAINST BACTERICIDAL PERMEABILITY-INCREASING PROTEIN IN INFLAMMATORY BOWEL-DISEASE/

Background-Bactericidal/permeability-increasing protein (BPI), a const ituent of primary neutrophil granules, is a potent natural antibiotic and an antineutrophil cytoplasm antibody (ANCA) antigen in cases of va sculitis in which the target antigen is neither myeloperoxidase (MPG) nor proteinase-3 (PR3). Aim-To investigate BPI as a possible target an tigen for ANCAs in inflammatory bowel disease. Methods-ANCAs were dete cted by routine immunofluorescence (IIF) and solid phase enzyme Linked immunosorbent assay (ELISA) performed for antibodies to the purified neutrophil granule proteins; MPO, PR3, cathepsin-G, lactoferrin, and B PI in serum samples from 88 patients with inflammatory bowel disease ( 36 with Crohn's disease, 52 with ulcerative colitis). Thirty patients with bacterial enteritis acted as controls. Results-Significantly more patients with ulcerative colitis were ANCA positive by IIF (60%) than patients with Crohn's disease (28%) or infectious enteritis (23%) (p< 0.001). IgG anti-BPI antibodies were present in 29% of patients with u lcerative colitis, 14% of patients with Crohn's disease, and 23% of pa tients with infectious enteritis, occurring in 44% of those patients w ith inflammatory bowel disease who were ANCA positive by IIF. Antibodi es to other ANCA antigens were rare. The presence of ANCAs was not rel ated to either disease activity or extent; presence of anti-BPI antibo dies was significantly related to both a lower serum albumin concentra tion (p=0.001) and a higher erythrocyte sedimentation rate (p=0.02) in patients with ulcerative colitis, and to colonic involvement in patie nts with Crohn's disease (p=0.01). Conclusion-BPI is a significant min ority Cambridge target antigen for ANCAs in inflammatory bowel disease that seems related to colonic Crohn's disease and disease activity in ulcerative colitis. Anti-BPI antibodies occur in infectious enteritis .