EVALUATION OF TC-99(M)-LABELED HUMAN-IMMUNOGLOBULIN IN ANIMAL-MODELS OF EXPERIMENTALLY-INDUCED INFLAMMATORY LESIONS

Human immunoglobulin (HIG) was labelled with Tc-99(m) using different Sn-ligand (methylene diphosphonate, MDP) in high yields. The effect of Sn:ligand ratios and protein (HIG) on the biodistribution pattern of Tc-99(m)-HIG in an animal model of turpentine-induced inflammatory les ions was studied. Tc-99(m)-HIG was excreted predominantly via the rena l pathway. The use of higher amounts of MDP and HIG resulted in relati vely slower blood clearance and increased uptake of Tc-99(m)-HIG in va rious organs. Also, higher amounts of ligand [Sn:MDP (1:5)] resulted i n significantly greater bone uptake (P < 0.001), while protein caused slower blood clearance and greater liver uptake. Despite the increased uptake of tracer in various organs, the ratio of inflamed:normal musc le uptake did not change significantly. A scintigraphic study was carr ied out with both Tc-99(m)-HIG and Tc-99(m) labelled with human serum albumin (HSA) in turpentine-induced inflammatory lesions produced in r abbits. The study revealed no significant differences in uptake early on, but the target:non-target ratio was higher with Tc-99(m)-HIG at 24 h. Tc-99(m)-HIG also had superior characteristics compared with Tc-99 (m)-HSA.