Immunoreactivity of alpha-1-antitrypsin in the human colon

Alpha-1-antitrypsin (AAT) was detected by an indirect immunofluorescent technique and a peroxidase antiperoxidase technique in the human colon. It was present along the luminal border, in Paneth cells, in occasional epithelial cells and in macrophages. In idiopathic inflammatory bowel diseases an increased number of AAT positive macrophages can be seen. Although AAT is scarcely present in the human it might play a role in a local defence mechanism and thus in the pathogenesis of inflammatory bowel diseases.