Development of Intestinal Mucosal Barrier Function to Antigens and Bacterial Toxins

Abstract

During the past several years our laboratory has attempted to define factors that contribute to the mucosal barrier of the intestine against the uptake of pathologic quantities of antigens and microbial organisms and their enterotoxins. It has become apparent from these studies that numerous components contribute to the collective exclusion of these noxious substances within the gut. Table 1 lists the components of the mucosal barrier as we currently envision it. It consists of numerous luminal factors such as gastric acid and peptic enzymes to minimize bacterial/ antigen penetration into the small intestine, and proteolytic pancreatic enzyme activity to decrease the protein antigen load to the mucosal surface. In addition to luminal factors, the mucosal surface, including the mucus layer, appears to be an important deterrent to the colonization of bacteria and to the attachment and uptake of foreign antigens. Finally, the unique secretory IgA antibody system is of major immunologic importance to the exclusion of antigens from the luminal surface (1,2).