Antineutrophil cytoplasmic autoantibodies in inflammatory bowel diseases.

Antineutrophil cytoplasmic autoantibodies have been recently reported in sera from patients with inflammatory bowel disease. We report our experience based on 90 patients with ulcerative colitis, 148 patients with Crohn's disease, and 60 controls. Determination of antineutrophil cytoplasmic autoantibodies was performed by the indirect immunofluorescence technique on ethanol fixed leucocytes. The specificities for proteinase 3, myeloperoxidase, and lactoferrin were tested by enzyme-linked immunosorbent assay. Forty-three out of 90 (48%) patients with ulcerative colitis, 10 out of 148 (7%) patients with Crohn's disease, and none of controls were positive by indirect immunofluorescence technique. All patients but two with positive immunofluorescence exhibited a perinuclear staining pattern. Among patients with ulcerative colitis, there was no relationship between the presence of perinuclear antineutrophil cytoplasmic autoantibodies and disease location or activity. Seven out of 20 (35%) patients with ulcerative colitis who had a previous colectomy (including 1 with ileoanal anastomosis) had perinuclear antineutrophil cytoplasmic autoantibodies. Antineutrophil cytoplasmic autoantibody specificity was not directed against myeloperoxidase, proteinase 3 or lactoferrin in sera from patients with inflammatory bowel diseases. Inflammatory bowel diseases are associated with a new subset of antineutrophil cytoplasmic autoantibodies. Among patients with Crohn's disease and ulcerative colitis, the sensitivity and specificity of the presence of perinuclear antineutrophil cytoplasmic autoantibodies for ulcerative colitis was 46% and 93%, respectively. Their presence reinforces the likelihood of underlying immunologic dysregulation in ulcerative colitis. Identification of the autoantigen(s) to which these antibodies are directed might facilitate the understanding of inflammatory bowel disease pathophysiology.