Description
Alpha-1 antitrypsin is an alpha-1 proteinase inhibitor that is expressed in the liver and the intestine.
Alpha-1 antitrypsin acts as an acute phase protein by inhibiting serine proteases, such as, elastase, trypsin, or chymotrypsin, and inflammatory processes by forming reversible complexes. In feces, alpha-1 antitrypsin is found both free or conjugated to either trypsin or elastase.
The higher concentration of proteinases in the feces is caused by an increased permeability of the intestinal epithelial layer, which in turn is set off by an abnormal array of the intestinal tight junctions that subsequently results in an enteral loss of plasma alpha-1 antitrypsin.
Fecal loss of alpha-1 antitrypsin has now become an accepted parameter for the evaluation of an enteral protein loss. Alpha-1 antitrypsin is a marker that is well suited for indicating changes of intestinal permeability in cases other than colitis or Crohn’s disease. Immunological processes in the intestinal mucous layer, that may be caused by food sensitivity, also result in an increase of fecal alpha-1 antitrypsin concentrations.