The antitumor monoclonal antibody MOv2 recognizes the Lewis A hapten.
Monoclonal antibody MOv2, produced against ovarian carcinoma, was previously found to bind a carbohydrate epitope (CAMOv2) present on mucins, glycoproteins and a neutral glycolipid. In this paper, the structure of the carbohydrate epitope is determined by immunological reactivity with purified glycolipids and oligosaccharides. Using solid-phase radioimmunoassay and immunostaining of thin layer chromatograms, MOv2 binds strongly to Le(a)-active pentasaccharide ceramide. A smaller neutral glycolipid also weakly binds MOv2. Fifty percent inhibition of binding to Le(a)-active pentasaccharide ceramide is achieved with approximately 8 microM concentration of lacto-N-fucopentaose II (LNF II). Lacto-N-tetraose (LNT) also partially inhibits at about 10(3) times higher concentration suggesting that the faster migrating glycolipid antigen contains this carbohydrate sequence. Binding to Le(a)-active hapten is further confirmed by the specific inhibition of binding by authentic anti-Le(a) monoclonal antibodies but not by anti-Le(b) MOv2 antibody in a serum assay among healthy blood donors also supports these results. In conclusion, we have obtained direct evidence from several independent experiments that antibody MOv2 recognizes the Le(a)-active hapten.
Leoni
F
F
Division of Experimental Oncology E Istituto Nazionale per lo Studio e la Cura dei Tumori, Milano, Italy.
Magnani
J L
JL
Miotti
S
S
Canevari
S
S
Pasquali
M
M
Sonnino
S
S
Colnaghi
M I
MI
D000911:Antibodies, Monoclonal / Q000276:immunology*; D000912:Antibodies, Neoplasm / Q000276:immunology*; D000941:Antigens / Q000276:immunology; D001667:Binding, Competitive; D002241:Carbohydrates / Q000276:immunology; D005260:Female; D006017:Glycolipids / Q000276:immunology; D006241:Haptens / Q000276:immunology; D006801:Humans; D007983:Lewis Blood Group Antigens / Q000276:immunology*; D009844:Oligosaccharides / Q000276:immunology; D010048:Ovarian Cysts / Q000276:immunology; D010051:Ovarian Neoplasms / Q000276:immunology
D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D000941:Antigens; D002241:Carbohydrates; D006017:Glycolipids; D006241:Haptens; D007983:Lewis Blood Group Antigens; D009844:Oligosaccharides