Anti - Saccharomyces cerevisiae ASCA (IgA)

ASCA IgA is an ELISA test to determine the quantity of anti-Saccharomyces cerevisiae (ASCA) IgA antibodies in human serum. These antibodies are directed against mannans in S. cerevisiae cell membrane.

ASCA test facilitates the differential diagnosis of inflammatory bowel disease, Crohn's disease and ulcerative colitis, especially in the early stage. Serum ASCA concentrations are significantly higher in Crohn's disease population versus to ulcerative colitis population. Studies show 75% of IgG-ASCA sensitivity and 60% for IgA-ASCA in Crohn's disease population. In contrast, IgG titers are increased in only 5% of ulcerative colitis population, and IgA titers in 7% only. Additional perinuclear anticytoplasmic antibodies (pANCA) test improves differential diagnosis: pANCA prevalence in ulcerative colitis is 50 to 90%, whereas it is only 10 to 20% in Crohn's disease.