Monoclonal antibody A7 coupled to magnetic particles as a contrast enhancing agent for magnetic resonance imaging of human colorectal carcinoma.
BACKGROUND
Local recurrence, the most frequent pattern of recurrence of rectal carcinoma, is almost always fatal. The difficulty of diagnosing local recurrence contributes importantly to the poor prognosis.


METHODS
We coupled monoclonal antibody (Mab) A7, which reacts specifically with human colorectal carcinoma, to ferromagnetic lignosite (FML) particles to distinguish rectal carcinoma from other tissues by magnetic resonance (MR) imaging. We examined retention of immunoreactivity by the A7-FML complexes in vitro, and also their distribution in vivo according to radiolabeling and MR imaging when injected into nude mice bearing human colorectal carcinoma xenografts.


RESULTS
A7-FML retained binding activity nearly identical to that of Mab A7. Significantly more (125)I-labeled A7-FML accumulated in engrafted tumors than did (125)I-labeled normal mouse IgG-FML complexes (P < 0.05). A7-FML disappeared rapidly from the blood. Normal tissues accumulated less (125)I-labeled A7-FML than tumors; this accumulation decreased linearly with time. In MR imaging, signal intensity was reduced in the tumor by the injection of A7-FML.


CONCLUSIONS
A7-FML is potentially useful as a MR contrast enhancing agent for human colorectal carcinoma xenografts implanted subcutaneously.
Otsuji
Eigo
E
Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan. otsuji@koto.kpu-m.ac.jp
Kuriu
Yoshiaki
Y
Okamoto
Kazuma
K
Ichikawa
Daisuke
D
Hagiwara
Akeo
A
Ito
Hirotoshi
H
Nishimura
Tsunehiko
T
Yamagishi
Hisakazu
H
D000818:Animals; D000911:Antibodies, Monoclonal; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging*; D003287:Contrast Media; D005290:Ferric Compounds; D006801:Humans; D018796:Immunoconjugates; D007457:Iodine Radioisotopes / Q000097:blood; D008279:Magnetic Resonance Imaging; D051379:Mice; D008819:Mice, Nude; D009374:Neoplasms, Experimental / Q000000981:diagnostic imaging; D011859:Radiography
D000911:Antibodies, Monoclonal; D003287:Contrast Media; D005290:Ferric Compounds; D018796:Immunoconjugates; D007457:Iodine Radioisotopes; C001215:ferrite