Anti-Saccharomyces Cerevisiae Antibodies and Autoimmune Diseases

The introduction of Anti-Saccharomyces Cerevisiae Antibodies (ASCA) in the past decade has provided a major diagnostic tool for the differentiation between Crohn's disease (CD) and Ulcerative colitis (UC) in inflammatory bowel disease (IBD) patients. Furthermore, ASCA may be useful in identifying IBD patients-relatives who are at risk for future development of the disease. Although ASCA were claimed to be quite specific for Crohn's disease, a growing number of studies have identified high levels of ASCA in several other autoimmune diseases—such as Behcet's disease, spondyloarthropathies, primary sclerosing cholangitis and celiac disease. This chapter discusses a panel of ASCA-associated diseases, of which Crohn's disease is the prototype one. There is yet no evidence that ASCA are involved in the pathophysiology of Crohn's disease—for example, by mediating cytotoxicity against intestinal epithelial cells. Instead, they may be the result of a cross-reactivity among the respective target antigen (or tissue) used for their detection and yet undetermined luminal antigens. The possible pathogenic potential of ASCA still awaits further studies in human patients as well as in experimental animal models.