title: Property and physiological role of biliary secretory IgA in rats.
abstract: Secretory IgA (sIgA) and monomeric IgA (mIgA) were purified from normal rat bile, and their role in the gastrointestinal tract was investigated. Biliary sIgA has a molecular weight of approximately 400,000 daltons and a sedimentation constant of 11.7S. Thus, sIgA obtained from rat bile had physicochemical properties similar to those reported for sIgA in other secretions, and probably consists of L-chains, alpha-chains and secretory component. After in vitro incubation with trypsin or intestinal fluid, sIgA remained intact, whereas mIgA was hydrolyzed. Rats challenged repeatedly with dinitrophenylated bovine serum albumin (DNP-BSA) had specific IgA antibody against DNP in the bile and feces as measured by a radioimmunoassay using [3H]-DNP-lysine. Our results demonstrate a possibility that biliary sIgA, not mIgA, has an important role which inhibits the absorption of foreign antigen from intestine.
mesh_terms: D000818:Animals; D001646:Bile / Q000502:physiology*; D007070:Immunoglobulin A / Q000302:isolation & purification / Q000502:physiology*; D007071:Immunoglobulin A, Secretory / Q000276:immunology / Q000302:isolation & purification / Q000502:physiology*; D007419:Intestinal Secretions / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012635:Secretory Component; D014357:Trypsin / Q000494:pharmacology; D014361:Trypsin Inhibitors; D005719:gamma-Globulins / Q000378:metabolism
chemical_list: D007070:Immunoglobulin A; D007071:Immunoglobulin A, Secretory; D012635:Secretory Component; D014361:Trypsin Inhibitors; D005719:gamma-Globulins; D014357:Trypsin