The demonstration of human tumors on nude mice using gadolinium-labelled monoclonal antibodies for magnetic resonance imaging.
OBJECTIVE
The authors describe the magnetic resonance imaging (MRI) of a tumor in a nude mouse tumor model by means of an antibody-polylysine (Gd-DTPA) conjugate.


METHODS
The monoclonal antibody, (MAB) RA96, was coupled to a polymeric gadolinium complex after periodate oxidation. This polymer, which consists of a polylysine backbone and complexing DTPA subunits, complexes an average of 65 gadolinium ions.


RESULTS
The immunoreactivity of the conjugates was reduced by an average of only 30% compared with the unbound MAB RA96. Biodistribution studies in nude mice with subcutaneously implanted human colon carcinomas (WiDr [specific] and HT29 [control]) revealed a tissue concentration in the specific tumor of 8.72% of the dose applied per gram despite the high molecular weight of the conjugates.


CONCLUSIONS
This tissue concentration is sufficient to achieve tumor-specific signal enhancement in the WiDr tumor on MRI. The problem of the high doses of protein required for MRI and possible solutions are discussed.
Göhr-Rosenthal
S
S
Institute of Diagnostic Research GmbH, Schering AG, Berlin, Germany.
Schmitt-Willich
H
H
Ebert
W
W
Conrad
J
J
D000818:Animals; D000911:Antibodies, Monoclonal; D003110:Colonic Neoplasms / Q000175:diagnosis*; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009942:Organometallic Compounds; D004369:Pentetic Acid / Q000031:analogs & derivatives*; D011107:Polylysine; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D009942:Organometallic Compounds; D011107:Polylysine; D004369:Pentetic Acid; D019786:Gadolinium DTPA