Different binding properties of three monoclonal antibodies to sialyl Le(x) glycolipids in a gastric cancer cell line and normal stomach tissue.

We established a mouse monoclonal antibody (Mab) KM93 which recognized sialyl Le x -carbohydrate epitope determined by solid phase radioimmunoassay using a panel of authentic glycolipids. The specificity of KM93 was similar to another anti-sialyl Le x Mab CSLEX-1 established previously, and- different from that of Mab FH6 which recognized sialyl Le x -i (sialyl dimeric Le x ). In a further study, however, we found that KM93 reacted with some glycolipids much more strongly than CSLEX-1 did on thin-layer chromatography (TLC) plates. We purified two gangliosides named K-1 and K-2 from gastric cancer cell line KATOIII, and three gangliosides named H-1, H-2, and H-3 from human stomach. KM93 reacted with all of these glycolipids