The etiology of Crohn’s disease remains unclear. It isthought to be caused by a combination of genetic, environmental and immunoregulatory factors. These factors lead to a wide variety of clinical presentations. The most notable is the dysregulation of the immune response to intestinal microbiota that contributes to the development of Crohn’s disease.

Cellular and humoral immune responses rely heavily on interactions between glycans (or carbohydrates) and specific glycan binding proteins. The IBDX^® test is a serological marker panel based on the detection of circulating antibodies directed against glycans. The panel consists of:
 ALCA - Anti Laminaribioside Carbohydrate Antibodies
 ACCA - Anti Chitobioside Carbohydrate Antibodies
 AMCA - Anti Mannobioside Carbohydrate Antibodies
 gASCA - Anti Saccharomyces Cerevisiae Antibodies

IBDX^® antibodies were found to respond to cell surface glycan antigens of fungal pathogens. gASCA and AMCA antibodies are directed against mannan antigens, which are found in the cell wall of the yeasts S. cerevisiae and Candidas albicans. ALCA and ACCA antibodies appear to be directed against glycans found in the cell wall of the pathogenic fungus Candidas albicans. Derivatives of chitobioside can also be found in crustaceans. Derivatives of laminaribioside can be found in oats. Derivatives of mannobioside can be found in bacteria and plants. All can play a role in Crohn’s Disease. 

IBDX^®glycan antibodies are elevated in serum of CD patients compared to ulcerative colitis patients and other gastrointestinal disease patients. Moreover, CD patients that are positive to 2 or more IBDX^® serologic markers are considered to be at more risk for a disease complication (stricturing or penetrating) or surgery intervention. Though the exact cause of these elevated antibody levels has not been deciphered, this phenomenon may be the result of the enhanced permeability of the epithelial layer of the gastrointestinal tract to pathogenic microorganisms.