Histochemical demonstration of O-glycosidically linked, type 3 based ABH antigens in human pancreas using lectin staining and glycosidase digestion procedures.

Histochemical analyses of the chemical structures of sugar sequences with or without blood group specificity were carried out by combined stepwise digestion of tissue sections with exo- and endoglycosidases and subsequent lectin stainings in formalin-fixed, paraffin-embedded human pancreas. In acinar cells from blood group A or AB secretor individuals, sequential digestion with alpha-N-acetylgalactosaminidase and alpha-L-fucosidase imparted reactivity with peanut agglutinin (PNA) in cells reactive with Dolichos biflorus agglutinin as well as those with Ulex europaeus agglutinin I(UEA-I). Simple fucosidase digestion imparted the PNA reactivity only in UEA-I reactive cells. Sequential digestion with alpha-galactosidase and fucosidase likewise liberated the PNA binding sites in Griffonia simplicifolia agglutinin I-B4 reactive cells from blood group B and AB secretors. Sialidase digestion liberated the PNA binding sites not only in acinar cells but also intercalated duct cells, islet cells of Langerhans and endothelial cells. The PNA reactivity obtained by these enzyme digestions was eliminted by endo-alpha-N-acetylgalactosaminidase (endo-GalNAcdase) digestion. Preexisting PNA affinity in acinar cells from non-secretors was also susceptible to endo-GalNAcdase treatment. Following the endo-GalNAcdase digestion, fucosidase or sialidase digestion recovered the PNA reactivity in acinar cells from nonsecretors. These results show that ABH determinants carried on O-glycosidically linked type 3 chain (D-galactose-(beta 1-3)-N-acetyl-D-galactosamine alpha 1-serine or threonine) are secreted in pancreatic acinar cells and suggest that product coded by the secretor gene is required for the complete conversion of type 3 precursor chains into H determinants.