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Serology in IBD

July 24, 2012 7:21 am

Serological antibodies against a number of antigens have shown some utility in differentiating inflammatory bowel disease (IBD) from non-IBD and in distinguishing Crohn’s disease (CD) from ulcerative colitis (UC).  A recent article evaluated 204 articles in a systematic review of these serological markers (Inflamm Bowel Dis 2012; 18: 1340-55).

The study has several useful tables and a long list of references.  In its Table 1, 10 serologies are listed with a range for prevalence in CD, UC, alternative GI conditions, and in healthy population.  Table 2 summarizes the data in terms of sensitivity, specificity, positive predictive value, negative predictive value for these antibodies in determining IBD from non-IBD.

With regard to specific antibodies, the review highlights 10 antibodies:

1. Anti-neutrophil cytoplasmic antibodies (ANCA).  Autoantibody directed against a constituent of neutrophil granules.  With IBD (especially UC), an atypical perinuclear (pANCA) staining pattern with indirect immunofluorescence and DNase-sensitive make this pattern different from ANCA due to vasculitis.

2-7. Anti-glycan antibodies –directed against cell wall microbes and reflect interaction between the immune system and glycosylated cell wall components of microbiota.

2. Anti-Saccharomyces cerevisiae (ASCA IgA and IgG) –antibodies directed against yeast cell wall.  While ASCA antibodies are commonly found in CD patients, 20-25% (or higher in some studies) of healthy relatives will test positive for these antibodies as well.  Approximately 6% of relatives of UC patients will be ASCA-positive.

3. Anti-laminaribioside carbohydrate IgG antibodies (ALCA) –antibodies directed against laminaribioside

4. Anti-chitobioside carbohydrate IgA antibodies (ACCA) –antibodies directed against chitobioside

5. Anti-mannobioside carbohydrate IgG antibodies (AMCA) –antibodies directed against mannobioside

6. Anti-L –antibodies directed against laminarin (large polysaccharide)

7. Anti-C –antibodies directed against chitin (large polysaccharide)

8. Anti-OmpC.  OmpC is a transport protein of E coli

9. Anti-I2.  I2 is a Pseudomonas-associated antigen

10. Anti-CBir1.  CBir1 is a bacterial flagellin antigen

Conclusions:

• Serology has only limited value for the initial diagnosis of IBD.
• Serology has ‘better value’ in differentiating CD from UC, though there is substantial variability in serologic responses in both diseases.  Probably, serology is most useful in unclassified IBD (IBD-U) in preoperative setting; serology may help predict risk of developing complications among patients undergoing pouch surgery.
• Serology is useful in predicting a complicated disease course. The presence and magnitude of these antibodies are strong predictors of disease progression.

Additional references:

• Pediatrics. 2010 Jun ;125 (6):1230-6.  Shortcomings of the inflammatory bowel disease Serology 7 panel. 
• -Clin Gastro & Hep 2008; 6: 1105. Increased immune reactivity/markers associated with aggressive disease.
• -IBD 2006; 12:1122. Expression of I2 antibodies (against a bacterial antigen of psedomonas fluorescens) was highly associated with clinical response to diversion. 15/16 with I2-pos had clinical response; 2/11 I2-neg had clinical response.
• -IBD 2008; 14: S4 abstract 0010. Practical experience with IBD serology (n=90) much less accurate than reported by Prometheus: overall accuracy of 63% (vs 92%), 66% sensitivity (vs 93%), 59% specificity (vs 95%), 75% PPV (vs 96%), and 49% NPV (vs 90%). In this population, 34% of known IBD were incorrectly predicted. Of 32 who did not have any evidence of IBD after clinical investigation, 40% (13) were seropositive.
• -Clin Gastro & Hep 2008; 6: 1105. Increased immune reactivity/markers associated with aggressive disease.
• -IBD 2008; 14; 129. Serologic markers not very useful clinically.
• -Pediatrics 2007; 119: e193. IBD serology performed poorly in comparison to combination of Hgb/ESR with regard to sensitivity (60% vs. 83%), specificity (92% vs. 96%), positive predictive value (60% vs. 79%) for IBD in children, n=227. Also one third of all positive serology in patients w/o IBD. The positive predictive value in patients w/o rectal bleeding was 35% vs 60% for routine tests.
• -Gastroenterol 2006; 131: 366. antibodies against laminaribioside, chitobioside, and mannan have predictive value in detecting Crohn’s disease.
• -Gastroenterol 2006; 130: 1078. Unaffected relatives positive for either OmpC or ASCA in 20% in large cohor (n=619 unaffected relatives. OmpC present in up to 44% of CD pts, up to 24% of UC pts, and 6% of controls.

Posted by gutsandgrowth

Categories: inflammatory bowel disease

Tags: ANCA, anti-C, anti-L, ASCA, CBir1, Crohn's, OmpC, Ulcerative colitis

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2 Responses to “Serology in IBD”

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   By How helpful are serologies in pediatric inflammatory bowel disease? | gutsandgrowth on August 31, 2016 at 7:07 am

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