Serologic abnormalities in IBD
What serologic abnormalities are seen in patients with IBD?
• Inflammatory markers: erythrocyte sedimentation rate and C-reactive protein are elevated.
• Autoantibodies: antineutrophil cytoplasmic antibody (ANCA), specifically perinuclear ANCA (pANCA), is seen in 55% to 70% of UC patients and <20% of colon-predominant Crohn’s patients. It is directed against lactoferrin and less commonly bactericidal permeability-increasing protein, cathepsin G, lysozyme, or elastase. It is never directed against myeloperoxidase. Rheumatoid factor and ANA are negative.
• Antibodies to microorganisms: anti- Saccharomyces cerevisiae (ASCA) are present in 40% to 70% of Crohn’s disease patients and <15% of UC patients. Antibodies to Escherichia coli outer membrane protein C (OmpC) and flagellin (CBir1, Af-Fla2, Fla-X) are found in 50% to 60% of Crohn’s and 5% to 10% of UC patients.