Analysis of Serum Antibodies in Patients Suspected of Having Inflammatory Bowel Disease

Abstract

Inflammatory bowel disease (IBD) is the general term used for a heterogeneous group of intestinal disorders, including Crohn's disease (CD) and ulcerative colitis (UC). Serological markers such as anti-Saccharomyces cerevisiae antibodies (ASCA) and atypical perinuclear antineutrophilic cytoplasmic antibody (atypical pANCA) have proven useful in the diagnosis and differentiation of CD and UC. Immunoglobulin A (IgA) antibody directed against the outer membrane protein C (OmpC) of Escherichia coli is said by one group to have clinical utility in diagnosing IBD, specifically in ASCA-negative CD patients. Our objective in this study was to compare the results obtained from two separate laboratories offering similar IBD tests using sera from suspected IBD patients. One hundred ninety-seven sera received for IBD testing were included in the study. The agreement between the two laboratories was 93.4% for ASCA IgA, 90.9% for ASCA IgG, and 87.8% for atypical pANCA IgG. There were 25 sera with ASCA-negative/OmpC-positive results reported by one laboratory. Thirteen of these 25 (52.0%) ASCA-negative/OmpC-positive sera were also atypical pANCA positive (9 as determined by both laboratories, 3 by one, and 1 by the other). Atypical pANCA antibody is found primarily in IBD patients with UC and colon-limited CD (Crohn's colitis). We conclude that the ASCA and atypical pANCA assays showed good agreement between the two laboratories, but the data for ASCA-negative/OmpCpositive sera suggest that many (52.0%) of these patients were more likely to have had UC or Crohn's colitis based on the presence of an atypical pANCA.Crohn's disease (CD) and ulcerative colitis (UC) are the two major forms of inflammatory bowel disease (IBD). Both CD and UC are chronic, affecting children and adults (men and women almost equally), and are most common in northern Europe and North America. The onset of CD and UC is usually between the ages of 15 and 30, with a second, smaller peak of incidence between the ages of 50 and 70 (4, 23). Approximately 20% of individuals with CD have a biological relative with some form of IBD, and several reports have noted an increase in the prevalence of CD and UC in various geographic regions (2,17,24,36).Although there are many theories about the etiology of CD and UC, none have been proven. Many of the symptoms of CD and UC are similar, and diagnosis is often difficult, time-consuming, and invasive. Since CD and UC are treated differently, correct diagnosis and differentiation are medically important.Two serological markers have been found to have clinical utility in diagnosing IBD and aiding in the differentiation of CD from UC: anti-Saccharomyces cerevisiae antibody (ASCA) (immunoglobulin A [IgA] and/or IgG), using enzyme immunoassay (EIA) techniques, and antineutrophil cytoplasmic antibody (ANCA) (IgG) that demonstrates atypical perinuclear staining (pANCA), using indirect fluorescent-antibody assay (IFA) techniques. ASCA is directed against mannose sequences in the cell wall of Saccharomyces cerevisiae (26,35) and...

Predictive Value of Serologic Markers in a Population-based Norwegian Cohort with Inflammatory Bowel Disease

“…32 As expected, our study confirms that pANCA is UCassociated, but the prevalence is lower than that reported in referral-based studies. 1 This includes 1 study from Belgium where the same laboratory and method for ANCA analysis was used as in our study.…”

Serological markers in inflammatory bowel disease

“…Antibodies against E. coli OmpC were present in 24-55% of patients with CD, compared to 5-11% of patients with UC and 5% of healthy controls, respectively [95,96]. However, prevalences of 24% in UC and 20% in healthy subjects have been reported [97]. In CD, OmpC antibodies were associated with disease progression and duration, and with complicated small bowel disease (fibrostenosis, internal perforating disease and small bowel surgery).…”

“…There was a negative association with UC-like CD [96,98]. Associations of OmpC antibodies with ocular manifestations and use of azathioprine have recently been described [97]. Antibodies against OmpC have been suggested to be able to identify ASCA negative CD patients.…”

Clinical significance of inflammatory markers

“…In UC, sensitivity was 60% and specifi city was 90% for ASCA -/p-ANCA + [6]. Reproducibility is an important feature of a diagnostic test; one study demonstrated 90% agreement between two laboratories for p-ANCA and ASCA [7].…”