Biodistribution of indium-111-labeled antibody directed against intercellular adhesion molecule-1.
We examined the biodistribution in normal rats of an 111In-labeled mouse monoclonal antibody to rat intercellular adhesion molecule-1 (111In-alCAM-1), as a potential detector of inflammation.


METHODS
Indium-111-alCAM-1 or 111In-labeled normal mouse polyclonal immunoglobulin G (111In-nmIgG) was injected into rats. Groups of three to four rats were killed up to 18 hr after injection, and activity was measured in various tissues. Rats were also imaged at 1 and 18 hr after injection.


RESULTS
Uptake of 111In-alCAM-1 was greatest in the lung (approximately 10% injected dose [ID]/g at 15 min) and then declined steadily (to approximately 2% ID/g at 18 hr). Lung uptake of 111In-nmIgG was eightfold less than that for 111In-alCAM-1 and did not change throughout the 18 hr. At all time points, blood activity for 111In-alCAM-1 was only 30% to 40% of that for 111In-nmIgG, whereas the percent injected dose per gram was increased more than twofold in the major organs. Compared with 111In-nmIgG, the 111In of alCAM-1 was shifted from the blood and was distributed among the lung kidney, spleen and liver.


CONCLUSIONS
Indium-111-alCAM-1 may be useful as an early inflammation detection agent. Intercellular adhesion molecule-1 upregulation is a very early event in inflammation and rapid removal from the blood of this antibody provides low background in contrast to the usual high background with whole antibodies.
Sasso
D E
DE
Department of Nuclear Medicine, University of Connecticut Health Center, Farmington 06030, USA.
Gionfriddo
M A
MA
Thrall
R S
RS
Syrbu
S I
SI
Smilowitz
H M
HM
Weiner
R E
RE
D000818:Animals; D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D007205:Indium Radioisotopes; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology*; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D051379:Mice; D016719:Radioimmunodetection; D051381:Rats; D011916:Rats, Inbred F344; D013997:Time Factors; D014018:Tissue Distribution
D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D007205:Indium Radioisotopes; D018799:Intercellular Adhesion Molecule-1