title: Histochemical reactivity of soybean agglutinin with blood group antigens and their precursor substances in acinar cells of human pancreas.
abstract: In human pancreas, soybean agglutinin (SBA) conjugated to horseradish peroxidase reacted with the acinar cells secreting blood group A and/or H antigen, but not with those secreting only B antigen. For detailed histochemical characterization of SBA staining, the effects of treatment with unlabeled lectins and of digestion of certain enzymes on SBA staining were investigated in formalin-fixed, paraffin-embedded pancreatic tissue from individuals of different blood groups. Pre-incubation of sections with unlabeled Dolichos biflorus agglutinin to block A antigen eliminated subsequent SBA staining in the cells secreting A antigen, although failing to induce any effects in those secreting H antigen. In contrast, pre-incubation with unlabeled Ulex europaeus agglutinin-I (UEA-I) to block H antigen abolished SBA staining in cells secreting H antigen but not in those secreting A antigen. Treatment with galactose oxidase yielded the same results as those with unlabeled UEA-I, i.e., SBA reactivity was significantly diminished in cells secreting H antigen but not in those secreting A antigen. Digestion with beta-galactosidase resulted in a slight decrease of SBA staining in the cells secreting H antigen. Accompanying the decrease of SBA staining, reactivity with Griffonia simplicifolia agglutinin-II (GSA-II) appeared for the first time in the enzyme-susceptible, SBA-reactive cells secreting H antigen. Pre-treatment with galactose oxidase abolished this effect of beta-galactosidase. The GSA-II reactivity disclosed by treatment with galactosidase was completely eliminated by digestion with beta-N-acetylhexosaminidase, indicating that GSA-II staining after digestion with galactosidase is due to exposed penultimate beta-N-acetyl-D-glucosamine residues. These results demonstrate that at least two substances react with SBA in acinar cells of human pancreas, one being terminal beta-N-acetyl-D-galactosamine residues of A antigen, and the other being terminal beta-D-galactose-(1----3 or 1----4)-beta-N-acetyl-D-glucosamine dimers in the precursor of blood group H antigen. Such dimers may exist in close proximity to L-fucose residues of H antigen, since unlabeled UEA-I blocked SBA staining.
mesh_terms: D000017:ABO Blood-Group System; D002240:Carbohydrate Sequence; D005692:Galactose Oxidase / Q000378:metabolism; D006651:Histocytochemistry; D006801:Humans; D037102:Lectins; D007983:Lewis Blood Group Antigens; D009439:Neuraminidase / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism; D010179:Pancreas / Q000166:cytology / Q000378:metabolism*; D037121:Plant Lectins; D030262:Soybean Proteins; D001616:beta-Galactosidase / Q000378:metabolism; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism; D010835:Phytohemagglutinins
chemical_list: D000017:ABO Blood-Group System; D005692:Galactose Oxidase; D037102:Lectins; D007983:Lewis Blood Group Antigens; D009439:Neuraminidase; D009844:Oligosaccharides; D037121:Plant Lectins; D030262:Soybean Proteins; D001616:beta-Galactosidase; D001619:beta-N-Acetylhexosaminidases; C028824:soybean lectin; D010835:Phytohemagglutinins