Solubilization of membrane-associated tumour-specific antigens by β-glucosidase

Abstract

The effects of various enzyme treatments on aminoazo dye-induced rat hepatoma cells or cell membranes, and the resulting degradation or solubilization of membrane-associated tumour-specific antigen are described. Both papain and β-glucosidase showed the capacity to liberate water-soluble antigenic products. Further fractionation by ion-exchange column chromatography of the soluble extract isolated by limited β-glucosidase digestion of hepatoma membranes, resolved the antigenic activity in a discrete region of the column eluate which was separated from the fractions displaying enzymic activity. This soluble antigenic material although heterogeneous by polyacrylamide-gel electrophoresis, retained the capacity both to inhibit the reaction of antibody in hepatoma-immune serum with cell surface-expressed antigens on viable hepatoma target cells in the membrane immunofluorescence test and also to elicit specific humoral antibody production in immunized animals. Tests were designed to analyse the mechanism of antigen solubilization by β-glucosidase and the results of these are discussed in view of the present understanding of the nature of tumour-specific antigens associated with aminoazo dye-induced rat hepatomas.