Abstract |
Technetium-99m labeling method using bifunctional
chelat.ing agent cyclicDTPA has been evaluated with
human polyclonal nonspecific IgG. IgG was conjugated
with cyclic DTPA with various molar ratio. Reduction of
Tc was done with Na,S,O, with various molar excesa
Labeling efficiency and identification of polymer was
confirmed with HPLC using TSK4000 SW column. Polymer
was purified with 100 cm Sepharose 6LB column. Cultured
1x10' Staphylococcus aureus were injected into rat
thigh 24 hours later labeled 1gG was injected, and in
vivo distribution was observed 4 and 24 hours
thereafter. Reduction of 99mTc was optimal with the
10000-50000 times molar excess of Na2S2O4, Polymer
formation increased with increasing mloar excess of
cyclic DTPA to IgG. Three step labeling-labeling DTPA
conjugated IgG after reduction of 99mTc-rnade more
polymer than two two step labeling-simultaneous mixing
DTPA conjugated IgG, 99mTc and Na2S2O4,. Tc b]ood
clearance and lower uptake in the abscess and other
organa. IgG conjugated with 200 times molar excess of
cyclic DTPA showed slower blood clearance with 200
times molar excess of cyclic DTPA showed slower blaod
clearance than that of 200 times molar excess of cyclic
DTPA showed slower blood clearance than that of 20
times molar excess. In the 99mTc labeling of IgG with
cyclic DTPA for the immunoscintigraphy,
obtimalllabeling condition should be chosen, and effect
of the ' Tc labeled IgG polymer should be considered. |