Technetium-99m-human polyclonal IgG radiolabeled via the hydrazino nicotinamide derivative for imaging focal sites of infection in rats.
The biologic behavior of human polyclonal immunoglobulin (IgG) radiolabeled with technetium-99m (99mTc) by a novel method, via a nicotinyl hydrazine derivative, was evaluated in rats. Technetium-99m- and indium-111-IgG were co-administered to normal rats and biodistribution was determined at 2, 6, and 16 hr. The inflammation imaging properties of the two reagents were compared in rats with deep-thigh infection due to Escherichia coli. Blood clearance of both antibody preparations was well described by a bi-exponential function: (99mTc-IgG: t1/2 = 3.82 +/- 0.89 and 57.52 +/- 1.70 hr. 111In-IgG: 3.93 +/- 0.117 and 40.71 +/- 1.26 hr). Biodistributions in the solid organs were similar, however, small but statistically significant differences were detected: 99mTc-IgG greater than 111In-IgG in lung, liver, and spleen; 99mTc-IgG less than 111In-IgG in kidney and skeletal muscle (p less than 0.01). At all three imaging times, target-to-background ratio and percent residual activity for the two compounds were remarkably similar. These studies establish that human polyclonal IgG labeled with 99mTc via a nicotinyl hydrazine modified intermediate is equivalent to 111In-IgG for imaging focal sites of infection in experimental animals.
Abrams
M J
MJ
Department of Radiology, Massachusetts General Hospital, Boston 02114.
Juweid
M
M
tenKate
C I
CI
Schwartz
D A
DA
Hauser
M M
MM
Gaul
F E
FE
Fuccello
A J
AJ
Rubin
R H
RH
Strauss
H W
HW
Fischman
A J
AJ
D000818:Animals; D004355:Drug Stability; D004927:Escherichia coli Infections / Q000000981:diagnostic imaging*; D006801:Humans; D007136:Immunoglobulins / Q000493:pharmacokinetics; D007553:Isotope Labeling / Q000379:methods*; D008297:Male; D011877:Radionuclide Imaging; D051381:Rats; D011919:Rats, Inbred Strains; D013667:Technetium / Q000493:pharmacokinetics; D014018:Tissue Distribution
D007136:Immunoglobulins; C065376:technetium Tc 99m immunoglobulin; D013667:Technetium