Polyclonal human immunoglobulin G labeled with polymeric iron oxide: antibody MR imaging.
Human polyclonal immunoglobulin (Ig) G was attached to a monocrystalline iron oxide nanocompound (MION), a small superparamagnetic probe developed for receptor and antibody magnetic resonance (MR) imaging. The resulting complex, MION-IgG, had a slightly negative surface charge, a molecular weight of 150-180 kDa, and 0.36 microgram of IgG attached per milligram of iron. After intravenous administration of MION-IgG to normal rats, most of the compound localized in liver, spleen, and bone marrow. In an animal model of myositis, MION-IgG caused reduced signal intensity (most apparent on T2-weighted spin-echo and gradient-echo images) at the site of inflammation. No change in signal intensity existed after an injection of unlabeled MION. Site-specific localization of MION-IgG was corroborated with scintigraphic imaging with indium-111 IgG and MION-In-111-IgG and was confirmed histologically with iron staining. These results indicate that antibody MR imaging is feasible in vivo. Target-specific and antibody MR imaging could be easily extended to other applications, including detection of cancer, infarction, and degenerative diseases.
Weissleder
R
R
Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown 02129.
Lee
A S
AS
Fischman
A J
AJ
Reimer
P
P
Shen
T
T
Wilkinson
R
R
Callahan
R J
RJ
Brady
T J
TJ
D000818:Animals; D003287:Contrast Media; D003911:Dextrans; D052203:Ferrosoferric Oxide; D006801:Humans; D007074:Immunoglobulin G; D007205:Indium Radioisotopes; D007501:Iron; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D009220:Myositis / Q000175:diagnosis; D010087:Oxides; D011108:Polymers; D051381:Rats
D003287:Contrast Media; D003911:Dextrans; D007074:Immunoglobulin G; D007205:Indium Radioisotopes; D058185:Magnetite Nanoparticles; D010087:Oxides; D011108:Polymers; C044411:polymeric IgG; D007501:Iron; C065507:ferumoxides; D052203:Ferrosoferric Oxide