The most important chronic inflammatory bowel diseases (CIBD) include ulcerative colitis (UC) and Crohn's disease (CD).
UC belongs to the genetically predisposed CIBD with autoimmune reactions against the mucosa and submucosa of the colon or rectum and increased immune reactions against the intestinal flora. The inflammation spreads continuously from the rectum, that is from the anal region upwards.
CD is classified as an autoimmune disease of the intestinal mucosa and is among the CIBD with a high recurrence rate. The chronic granulomatous inflammation, which can affect the whole digestive tract from the oral cavity to the anus, is found in most cases only in the lower small intestine (terminal ileum) and the large intestine (colon), very rarely in the oesophagus and mouth. A discontinuous, segmental attack on the intestinal mucosa, with several sections of the intestine being affected simultaneously, is characteristic for CD.
Differential diagnostics are, along with targeted diagnostics, essential for the differentiated diagnosis of CIBD. The high diagnostic requirements are met by IIFT single assays as well as by various highly specific IIFT mosaics (CIBD profiles), which have been developed especially for the serological diagnosis of the autoimmunological bowel diseases CD and UC.
Autoantibodies against acinus cells of the exocrine pancreas are a reliable marker for CD. They have a high disease-specific significance due to their organ specificity, disease association and frequently high serum concentration. Due to the fact that the inflammation of the intestinal wall in CD is caused by the autoantigens contained in the pancreas secretion, particularly the proteoglycans CUZD1 and GP2, the determination of autoantibodies against the pancreas antigens rPAg1 (CUZD1) and/or PAg2 (GP2) using IIFT represents a new dimension in the serological diagnosis of CD. Antibodies against Saccharomyces cerevisiae (ASCA) enrich the serological diagnosis of CD by a further specific parameter.
Autoantibodies against intestinal goblet cells, which occur exclusively in UC, are pathognomonic markers for this autoimmune disease. The target antigen responsible for UC has not yet been exactly identified. The serological determination of autoantibodies against DNA-bound lactoferrin contributes significantly to the diagnosis of CIBD, particularly of UC.