Recognition of bactericidal/permeability-increasing protein by perinuclear anti-neutrophil cytoplasmic antibody-positive sera from ulcerative colitis patients: Prevalence and clinical significance

Background: The aim of this study was to evaluate a) the role of bactericidal/permeability-increasing protein (BPI) as a possible antigen determining perinuclear anti-neutrophil cytoplasmic antibody (p-ANCA) reactivity in ulcerative colitis and b) the prevalence and clinical correlates of anti-BPI antibodies in patients with ulcerative colitis on the basis of their p-ANCA status. Methods: p-ANCA and anti-BPI antibodies were evaluated by means of indirect immunofluorescence and enzyme-linked immunosorbent assay methods in a group of 112 ulcerative colitis patients (including 42 patients subjected to proctocolectomy) well defined as far as their clinical features and p-ANCA status. Results: Anti-BPI antibodies were detected in 24% of non-operated patients and were significantly more frequent in p-ANCA-positive patients (32% versus 5% in p-ANCA-negative patients; P < 0.015). The prevalence of anti-BPI antibodies was similar in non-operated and operated patients and was high in men, in patients with an extensive and aggressive disease, and in patients developing pouchitis after surgery. Conclusions: These data indicate that BPI is a neutrophil antigen frequently recognized by p-ANCA-positive ulcerative colitis sera. The presence of anti-BPI antibodies appears to identify further immunologic and clinical heterogeneity in ulcerative colitis.