Anti-neutrophil cytoplasmic autoantibodies (ANCA) to bactericidal/permeability-increasing (BPI) protein recognize the carboxyl terminal domain

Abstract Objectives : to identify the region of bactericidal/permeability-increasing protein (BPI) recognized by anti-BPI AN CA. Methods : sera from 140 patients with a variety of clinical diagnoses (20 systemic vasculitis, 12 cystic fibrosis, 22 bronchiectasis/chronic obstructive airways disease, three diabetes mellitus, 13 chronic renal failure, 12 primary sclerosing cholangitis, eight ulcerative colitis, three Crohn's disease, seven cancer, and 40 other or unknown diagnoses) known to be reactive against native (nBPI), were screened by solid phase enzyme linked immunosorbent assay (ELISA) against a panel of recombinant fusion proteins; holo BPI (rBPI), recombinant lipopolysaccharide binding protein (rLBP), an N-terminal fragment of rBPI (rBP12 I) and ‘fusion' proteins containing the C- or N-terminal ends of BPI spliced with N- or C-ends of LBP, respectively. Results : a strong correlation was seen between the degree of reactivity to rBPI and the BPI C-terminal fusion protein, r = 0.69, P r = 0.55, P Conclusions : together these data suggest that circulating autoantibodies to BPI from patients with different diseases recognize the C-terminal region of BPI.