Monoclonal antibody GOM-2 binds to blood group B-Le(y) active glycolipid antigens on human gastric cancer cells, KATO-III.

The antigen structure of a mouse monoclonal antibody, GOM-2, established by immunization with KATO-III human gastric cancer cells, was examined. GOM-2 reactive glycolipids were prepared from KATO-III cells and treated with endoglycoceramidase. Structural studies of ten GOM-2 reactive oligosaccharides by a combination of glycosidase digestions, methylation, and affinity chromatography on an Ulex europeus agglutinin I (UEA-I) column revealed that nine of them had a Y-related B-active difucosylated determinant (B-Le(y)) and one had a B-active determinant. Affinity chromatography of the purified and modified oligosaccharides on an immobilized GOM-2 column demonstrated that GOM-2 has a novel binding specificity: it binds tightly to the biantennary structure carrying the B-Le(y) determinant at the termini or the branched structure carrying the B-Le(y) structure at two nonreducing termini.