Neutral α-Glucosidase in Granule Fractions from Guinea Pig Polymorphonuclear Leukocytes: Enzymic Characterization and Comparative Studies with Monoclonal Antibodies

Abstract

Neutral a-glucosidase was partially purified from granular fractions isolated from guinea pig polymorphonuclear leukocytes (PMNL). The native enzyme had a high molecular weight, about 417, 000, with a subunit of 43, 000. The purified enzyme hydrolysed 4-methylumbelliferyl a-glucoside and maltose, but not isomaltose, trehalose, and glycogen. The enzyme was strongly inhibited by bromoconduritol and castanospermine, but only slightly by turanose. Monoclonal antibodies which can bind specifically to the enzyme were prepared by immunizing mice with the partially purified enzyme. Hybridomas producing the monoclonal antibodies were selected by an enzyme-linked immunosorbent assay. The seven monoclonal antibodies were found to react with the enzyme from PMNL, but not with the glycoprotein-processing a-glucosidase isolated from liver microsomes nor with the macrophage enzyme. The results indicated that PMNL contain a particulate neutral a-glucosidase enzymologically and immunologically distinct from other a-glucosidases.