Characterization of the shed form of the human tumor-associated glycoprotein (TAG-72) from serous effusions of patients with different types of carcinomas.
Monoclonal antibody (MAb) B72.3 binds a high molecular weight tumor-associated glycoprotein designated TAG-72. This study reports the isolation and characterization of secreted TAG-72 directly from effusions of ovarian, colorectal, pancreatic, and endometrial carcinoma patients and compares them to TAG-72 derived from the LS-174T colon carcinoma xenograft. The B72.3-reactive antigen, TAG-72, was used as immunogen to produce second generation anti-TAG-72 MAbs. One of these second generation MAbs, CC49, had a higher affinity than that of B72.3 and was utilized as an affinity reagent in a procedure to purify the TAG-72 present in the serous effusions of carcinoma patients. A three-step purification procedure, utilizing heat extraction, CC49 antibody affinity chromatography, and gel filtration chromatography, resulted in 1000- to 4400-fold purifications of the TAG-72 derived from effusions, as analyzed using a double-determinant radioimmunoassay. Radiolabeled TAG-72 from each of the effusions demonstrated similar high molecular weight bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Similar results from the various effusions were also obtained in Western blotting analyses. Analyses of TAG-72 from the different effusions in radioimmunoassay using five different anti-TAG-72 MAbs revealed similar binding patterns. The results of these studies thus indicate that TAG-72 obtained directly from patients with ovarian, colorectal, endometrial, and pancreatic carcinomas and the LS-174T xenograft are highly similar in terms of immunochemical properties and antigenic profile.
Katari
R S
RS
Laboratory of Tumor Immunology and Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Fernsten
P D
PD
Schlom
J
J
D000818:Animals; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex / Q000032:analysis; D000951:Antigens, Neoplasm / Q000032:analysis* / Q000302:isolation & purification; D001201:Ascites / Q000276:immunology; D002460:Cell Line; D002850:Chromatography, Gel; D003110:Colonic Neoplasms / Q000032:analysis*; D004717:Endometrium / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005122:Exudates and Transudates / Q000032:analysis*; D005260:Female; D006023:Glycoproteins / Q000032:analysis* / Q000302:isolation & purification; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D010190:Pancreatic Neoplasms / Q000032:analysis*; D011863:Radioimmunoassay; D012004:Rectal Neoplasms / Q000032:analysis*; D014183:Transplantation, Heterologous
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D000951:Antigens, Neoplasm; D006023:Glycoproteins; C047052:tumor-associated antigen 72