TECHNETIUM-99M-HUMAN POLYCLONAL IGG RADIOLABELED VIA THE HYDRAZINO NICOTINAMIDE DERIVATIVE FOR IMAGING FOCAL SITES OF INFECTION IN RATS

  • 1 December 1990
    • journal article
    • research article
    • Vol. 31  (12) , 2022-2028
Abstract
The biologic behavior of human polyclonal immunoglobulin (IgG) radiolabeled with technetium-99m (99mTc) by a novel method, via a nicotinylhydrazine derivative, was evaluated in rats. Technetium-99m- and indium-111-IgG were coadministered 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-Ig: 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 > 111In-IgG in lung, liver, and spleen; 99mTc-IgG < 111In-IgG in kidney and skeletal muscle (p < 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 nicotinylhydrazine modified intermediate is equivalent to 111In-IgG for imaging focal sites of infection in experimental animals.