Immunochemical characterization of mucins. Polypeptide (M1) and polysaccharide (A and Leb) antigens.
Seven monoclonal antibodies (MAbs) reacting with high-molecular-mass components (greater than 20,000 kDa) isolated from an ovarian mucinous cyst of an A Le(a-b+) patient are described. By the use of immunoradiometric methods, these MAbs characterized seven different epitopes associated with components having a density of 1.45 g/ml by CsCl-density-gradient ultracentrifugation, like mucins. Two MAbs reacted with A and Lewis blood-group antigens respectively (polysaccharide epitopes). The five other MAbs characterized five M1 epitopes (called a, b, c, d and e), mainly associated with components of more than 20,000 kDa and 2000 kDa. They were completely destroyed by papain and 2-mercaptoethanol treatment (polypeptide epitopes). Moreover, timed trypsin digestion of native mucin resulted in a progressive loss of M1 activity and degraded these mucins into smaller M1-positive fragments. The a and c epitopes were partially degraded from relatively high-molecular-mass fragments (2000 kDa to 500 kDa) into a 100 kDa fragment. The b and d epitopes were completely degraded into smaller fragments ranging from 100 kDa to 40 kDa. The e epitope was completely destroyed by trypsin. These different pathways of M1 antigen degradation suggest the occurrence of different epitopes located in separate regions of the mucin molecules.
Bara
J
J
Institut de Recherches sur le Cancer, C.N.R.S., Villejuif, France.
Gautier
R
R
Le Pendu
J
J
Oriol
R
R
D000911:Antibodies, Monoclonal; D000941:Antigens / Q000032:analysis*; D002500:Centrifugation, Isopycnic; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000032:analysis; D006801:Humans; D008623:Mercaptoethanol / Q000494:pharmacology; D009077:Mucins / Q000276:immunology*; D010206:Papain / Q000494:pharmacology; D010455:Peptides / Q000276:immunology*; D011134:Polysaccharides / Q000276:immunology*; D011863:Radioimmunoassay; D014357:Trypsin / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D000941:Antigens; D000939:Epitopes; D009077:Mucins; D010455:Peptides; D011134:Polysaccharides; D008623:Mercaptoethanol; D014357:Trypsin; D010206:Papain