Antineutrophil cytoplasmic antibodies in children with inflammatory bowel disease: prevalence and diagnostic value

Antineutrophil cytoplasmic antibodies (ANCA), particularly perinuclear ANCA (p-ANCA), have been found more frequently in sera from patients with ulcerative colitis (UC) than in sera from Crohn's disease (CD) or unclassified enterocolitis (UE) patients. This 2-center study examined sera from 102 pediatric patients with inflammatory bowel disease (IBD) to evaluate their diagnostic value and assess their relationship with disease features, distribution, activity and treatment.

The serum ANCA of 102 children with IBD were measured: 33 UC, 64 CD and 5 UE with various disease locations and degrees of activity. The mean age at the onset of symptoms was 10.7 years (1 to 16.3 years). Sera from 26 unaffected first degree relatives and 20 children without IBD were also investigated. ANCA were detected using indirect immunofluorescence of ethanol-fixed granulocytes.

There were ANCA in the sera of 24/33 children with UC (73%), 9/64 with CD (14%) and 4/5 with UE (80%). p-ANCA were more frequent than cytoplasmic-ANCA in positive sera: UC = 67%, CD = 57% and UE = 75%. The presence of ANCA was 73% sensitive and 81% specific for a diagnosis of UC, compared to other IBD (p < 0.001). Three children with proved sclerosing cholangitis associated with UC were all positive. There was no link between ANCA-positive sera and disease activity, or other endoscopic or clinical criteria. ANCA were detected in 4/26 first degree relatives (15%) and in 1/20 control subjects (5%).

Because of their sensitivity and specificity, ANCA may be helpful in the clinical assessment of patients with IBD, and especially those with UC. However, there is no link between the pressure of p-ANCA and the site of UC or its activity, so that it cannot be used to monitor medical treatment or surgical indications.