RADIOIMMUNOSCINTIGRAPHY USING TC-99M-LABELED PARENTAL MOUSE AND MOUSE-HUMAN CHIMERIC ANTIBODIES TO CARCINOEMBRYONIC ANTIGEN IN ATHYMIC NUDE-MICE BEARING TUMOR
Y. Karube et al., RADIOIMMUNOSCINTIGRAPHY USING TC-99M-LABELED PARENTAL MOUSE AND MOUSE-HUMAN CHIMERIC ANTIBODIES TO CARCINOEMBRYONIC ANTIGEN IN ATHYMIC NUDE-MICE BEARING TUMOR, Nuclear medicine and biology, 23(6), 1996, pp. 753-759
Biodistribution and imaging characteristics of Tc-99m-labeled parental
mouse and mouse-human chimeric antibodies to carcinoembryonic antigen
(CEA), designated F11-39 and ChF11-39, respectively, were evaluated i
n athymic nude mice bearing the human CEA-producing gastric carcinoma
(MKN-45) xenografts. Group F monoclonal antibodies such as F11-39 and
ChF11-39 have been found to recognize the protein epitopes present on
the domain B3 of the CEA molecule and to discriminate CEA in tumor tis
sues from the CEA-related antigens. The Tc-99m labeling was performed
by immediately mixing a reduced antibody by 2-mercaptoethanol with Tc-
99m pertechnetate in the presence of stannous chloride. The labeling y
ields of the two antibodies were greater than 95% when estimated using
gel chromatography. Although these Tc-99m-labeled antibodies were sta
ble in neutral saline solution, Tc-99m from both labeled antibodies wa
s associated with cysteine solution. Technetium-99m ChF11-39 was more
susceptible to transchelation than was Tc-99m F11-39. The immunoreacti
vity of each Tc-99m-labeled antibody was confirmed using MKN-45 cell-b
inding assay. Biodistribution studies in tumor-bearing mice were perfo
rmed at 1 h, 5 h, and 20 h after being given IV injections of 3.7 MBq
of either Tc-99m F11-39 or Tc-99m ChF11-39. All tumor-to-organ uptake
ratios increased with time for both Tc-99m-labeled antibodies. Imaging
results also showed selective and progressive accumulation of both Tc
-99m antibodies at the tumor site. Both these Tc-99m-labeled antibodie
s have proved to be good radiotracers giving satisfactory scintigrams
of the CEA-producing tumor.