LOW-PREVALENCE OF ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES IN ULCERATIVE-COLITIS PATIENTS WITH LONG-TERM REMISSION

Objectives: In spite of a strong positive association between ulcerati ve colitis and the presence of perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCAs), the immunogenetic significance of these antibod ies remains unclear. We studied patients with quiescent disease to cla rify whether ANCAs are present even in the absence of inflammation. De sign: The prevalence of ANCAs was estimated blindly in 137 patients wi th ulcerative colitis, 128 of whom had quiescent disease with a mean d uration of complete clinical and biochemical remission of 14 years. Fo r comparison, we studied sera from 110 patients with Crohn's disease, 27 of whom had a low or intermediate grade of inflammatory activity. T he mean duration of complete remission in these patients was 8.5 years . Methods: ANCAs were detected using indirect immunofluorescence and e nzyme-linked immunosorbent assays (ELISAs). Results: Only 13 (9%) of 1 37 patients with ulcerative colitis had ANCAs (5% had p-ANCAs). Three patients had previously undergone colectomy. In patients with Crohn's disease, ANCAs were observed in 17 of 110 patients (15%, 6% had p-ANCA s). Fifteen of these patients had colonic disease. Conclusion: In pati ents with ulcerative colitis free from inflammation for prolonged peri ods of time, ANCAs occurred less frequently than has previously been r eported. Patients with Crohn's disease had the expected frequency of A NCA positivity, which for colonic Crohn's disease was comparable to th at found in patients with ulcerative colitis. These findings suggest t hat the titre of ANCAs decreases with time in inactive disease and may be undetectable with conventional assays after several years of compl ete remission.