Parameter
| Biomarker | Serum antibodies (anti-Saccharomyces cerevisiae ASCA, ANCA, AEA, etc) | Full name | Serum antibodies (anti-Saccharomyces cerevisiae antibody, antineutrophil cytoplasmic antibody, anti-enterocyte antibody, etc) | Molecular Type | Proteins (immunoglobulins, e.g., IgG, IgA) |
|---|---|---|---|---|---|
| Molecular Formula | Human ASCA (IgG/IgA): C₆₃₂H₉８₄N₁₆₄O₁₉６S₈ (IgG), C₆₂０H₉６２N₁６０O₁９２S₈ (IgA); ANCA (IgG): C₆₃₂H₉８₄N₁₆₄O₁₉６S₈; AEA (IgG): C₆₃₂H₉８₄N₁₆₄O₁₉６S₈ | Molecular Weight | ~150 kDa (IgG), ~160 kDa (IgA) | Core Functional Dimensions | Identification of IBD subtypes (CD vs UC), assessment of disease susceptibility, and association of disease severity |
| Disease | Inflammatory Bowel Disease (IBD) | Disease Subtypes | / | ||
| Organ | Intestine | Test Sample / Technology Platform | Serum (enzyme-linked immunosorbent assay ELISA, indirect immunofluorescence assay IIF, Western blot) | ||
| Pathobiological Mechanisms | The pathogenesis of IBD is closely related to intestinal flora imbalance and immune abnormalities: 1. Anti-saccharomyces cerevisiae antibody (ASCA) : Saccharomyces cerevisiae is a component of normal intestinal flora. Due to the damage of intestinal mucosal barrier, the yeast antigen enters the circulation of CD patients and induces the body to produce specific antibodies (mostly IgG/IgA), which is related to intestinal transmural inflammation, fistula formation and other complications of CD. 2. Antineutrophil cytoplasmic antibody (ANCA, mainly p-ANCA) : Due to the abnormal activation of neutrophils in UC patients, its cytoplasmic components are exposed and become autoantigens, inducing the body to produce autoantibodies, which is related to localized inflammation and mucosal erosion and ulcer in UC. Anti-enterocyte antibody (AEA) : The antibody against the surface antigen of intestinal epithelial cells can damage the intestinal barrier and aggravate inflammation. The positive rate of AEA in IBD patients is low, but it is positively correlated with the severity of the disease. | ||||
| Clinical Availability Status | Clinical use/guideline recommendation: as an important auxiliary indicator for the differentiation of IBD subtypes (CD vs UC), it has been included in the consensus on the diagnosis and classification of IBD, especially when the clinical manifestations are atypical and the subtypes are difficult to be distinguished by endoscopy and imaging, but it is not an independent diagnostic indicator. | ||||
| Notes and Dynamics | Serum antibodies (especially ASCA+ANCA combination) are the core auxiliary tools for the identification of IBD subtypes, which can effectively improve the accuracy of the identification of CD and UC, and provide reference for the selection of clinical treatment options (for example, CD is more likely to require biological agents, and UC can give priority to 5-aminosalicylic acid drugs). However, it should be noted that its sensitivity is limited (for example, the positive rate of ASCA in CD is about 40%-60%, and the positive rate of ANCA in UC is about 50%-70%), and it cannot be used alone for the diagnosis of IBD. In addition, some healthy people or patients with other autoimmune diseases (such as rheumatoid arthritis) may also have false positive results, which should be judged comprehensively by endoscopy, pathology and clinical symptoms. It is not recommended as a population screening index. | ||||