Anti-neutrophil cytoplasmic antibodies in Brazilian patients with inflammatory bowel disease

BACKGROUND/AIMS: Anti-neutrophil cytoplasmic antibody has been observed in the sera of patients with inflammatory bowel disease, but its prevalence depends on the population being studied and the method employed for its detection. METHODOLOGY: We evaluated the prevalence of antineutrophil cytoplasmic antibody by immunofluorescence assay in a series of Brazilian patients with inflammatory bowel disease: 40 patients with ulcerative colitis and 36 with Crohn's disease. We also correlated the presence of this antibody with duration of symptoms, site of the disease and inflammatory activity. Thirty healthy individuals comprised the control group. RESULTS: Anti-neutrophil cytoplasmic antibody was detected in 27.5% of the patients with ulcerative colitis, and in 14.3% of those with Crohn's colitis. Perinuclear staining pattern was the most common, but atypical and nuclear patterns were also observed. There was no correlation between the presence of this antibody and any of the studied clinical variables. No patient of the control group presented positive test. CONCLUSIONS: A positive anti-neutrophil cytoplasmic antibody test would not be helpful in the differential diagnosis between ulcerative colitis and Crohn's colitis, since it has a moderate specificity of 86% for ulcerative colitis patients.