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Anti-''Saccharomyces cerevisiae'' antibodies (ASCAs) are antibodies against antigens presented by the cell wall of the yeast ''Saccharomyces cerevisiae''. ASCAs and perinuclear antineutrophil cytoplasmic antibodies (pANCAs) are the two most useful and often discriminating biomarkers for colitis. ASCA tends to recognize Crohn's disease more frequently, whereas pANCA tend to recognize ulcerative colitis. ASCA antibodies react to a protein called a yeast mannan, a 200-kDa glycoprotein. Diseases in which ASCA are found include the following: * Behçet's disease - The association with ASCA is not generally strong, but increased in patients with gastrointestinal symptoms. *Celiac disease * Colitis〔 * * Ulcerative colitis-familial. * * Microscopic colitis * * * Collagenous colitis *Crohn's disease Intestinal yeast and ASCA+. Intestinal yeast infections are seen in malabsorptive diseases like coeliac disease. In Crohn's disease and ulcerative colitis the presence of intestinal ''S. cerevisiae'' is rare, but the association with irritiable bowel in coeliac disease remains unstudied. ==Anti-mannans== Mannan (oligomannan) is a component of the yeast cell wall. Antibodies to yeast mannans are found at increased frequency in Crohn's disease and ASCA+ Crohn's tend to have lower low levels of mannan-binding lectin. Experimentally, antibodies to mannans from yeast can also crossreact to mannans of other types of yeast. Study of the sugars indicated that a mannotetraose (4-mer) was responsible for highest response. Studies of the 200 kDa glycoprotein antibodies found them commonly in healthy people, suggesting that the disease associated antibodies are to their carbohydrate moieties. Mannans from other yeast, for example ''candida albicans'', have found to cross react with ASCA which suggests that other yeast may induce ASCA associated diseases. Mannan-binding lectin (MBL) is a lectin produced by humans. In ASCA+ Crohn's disease the serum level of this protein is lower. Cellular response to mannan in ASCA+ peripheral blood lymphocytes could be inhibited by adding MBL, however, a high frequency of mutations in the MBL gene was found in ASCA+ patients. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Anti–Saccharomyces cerevisiae antibody」の詳細全文を読む スポンサード リンク
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