Establishment and characterization of monoclonal antibodies to carbohydrate antigens on peanut agglutinin receptor glycoprotein of gastric cancer KATO-III.

Eight mouse monoclonal antibodies, GOM-1, GOM-2, GOM-3, GOM-5, GOM-6, GOM-7, GOM-8 and GOM-9 were established that recognized carbohydrate antigens on the human gastric cancer cell line KATO-III. Their binding specificities were studied by enzyme-linked immunosorbent assay, cellular enzyme-linked immunosorbent assay, flow cytometry analysis and thin layer chromatography immunostaining. All these monoclonal antibodies bound to peanut agglutinin receptor glycoproteins and neutral glycolipids extracted from KATO-III cells, but they could be divided into three groups, namely GOM-1, -3, -9 group, GOM-5 and GOM-2, -6, -7, -8 group. GOM-3 specifically bound to the Le(a) structure, Gal beta 1-3 (Fuc alpha 1-4) GlcNAc beta 1-, and GOM-5 specifically bound to the Lec structure, Gal beta 1-3GlcNAc beta-. GOM-2 showed specific binding to KATO-III, but little or no binding to various other cell lines examined or to normal human leukocytic cells. It also did not bind to the synthetic glycoconjugates tested, carrying 10 different terminal sugar chains including T, Tn, Le(a), Lec and Le(x) structures. The binding specificity of GOM-2 was also different from those of the monoclonal antibodies anti-Le(x), anti-Leb and anti-Ley. These results suggest that GOM-2 recognizes a new carbohydrate antigen on KATO-III cells that is distinct from Le(a), Leb, Lec, Le(x), Ley, T and Tn structures.