Direct labeling of monoclonal antibodies with 99mTc and radioimmunodetection of a murine mammary carcinoma with 99mTc-B2C114.
Two anti-CEA antibodies, B2C114 and IORCEA1, were radiolabeled with 99mTc by two direct methods (mercaptoethanol and ascorbic acid reduction), and the radio-immunoimaging properties of B2C114 were assessed in mice bearing an M3-reactive tumor. The labeling efficiency was greater than 90% as measured by ITLC in saline, methylethylketone and with serum albumin impregnated sheets using ethanol: water: NH4OH (2:5:1). The label was stable to challenge with excess DTPA, and in the case of ascorbic acid reduction, serum analysis showed that 10-15% of the radioactivity was lost during incubation. In vitro studies demonstrated that the radiolabeled antibodies retained their immunoreactivity. Biodistribution studies in normal Balb/c mice showed that the pattern of uptake was quite similar for both antibodies. Biodistribution of the 99mTc-B2C114 and image studies in the animal model showed that the tumor was clearly visualized and that B2C114 labeled with 99mTc is a possible candidate for human radioimmunodetection of CEA-expressing tumors.
Duran
A P
AP
Oncologic Center of Nuclear Medicine, Institute of Oncology, Angel H. Roffo, Buenos Aires, Argentina.
Asurmendi
S
S
D'Orio
E
E
Horenstein
A L
AL
de Castiglia
S G
SG
D000818:Animals; D000911:Antibodies, Monoclonal; D002272:Carcinoembryonic Antigen / Q000276:immunology; D005260:Female; D007553:Isotope Labeling / Q000379:methods; D008325:Mammary Neoplasms, Experimental / Q000000981:diagnostic imaging*; D051379:Mice; D008807:Mice, Inbred BALB C; D015609:Organotechnetium Compounds; D011817:Rabbits; D016719:Radioimmunodetection; D014018:Tissue Distribution
D000911:Antibodies, Monoclonal; D002272:Carcinoembryonic Antigen; D015609:Organotechnetium Compounds