Comparative tissue distribution of 125I- and U-14C-labeled recombinant human interleukin-2 in the rat.
The distribution of recombinant human interleukin-2 (rhIL-2) after intravenous administration of 125I- or U-14C-labeled rhIL-2 is reported in the major organs of the rat. Five minutes after the administration of U-14C-labeled rhIL-2, the radioactivity had been rapidly cleared from the plasma, while 38% of the dose was found in the kidneys, confirming that the major site of clearance for rhIL-2 is the kidney. After 1 h, a large fraction of the radioactivity had disappeared from the kidney and was found in the carcass. When the same experiments were carried out with 125I-labeled rhIL-2, comparable distribution results were obtained: Preferential accumulation of 125I radioactivity (37.4%) was found in the kidney at 5 min after iv administration of 125I-labeled rhIL-2. One hour after dosing 125I label was predominantly present in the carcass (46%) and skin (15%). Similar percentages of the dose of 125I or 14C radioactivity were present in other organs or tissues. The present study indicates a similar distribution of the radiolabel in selected tissue and organs regardless of whether 14C or 125I was employed.
Sabo
J
J
Department of Drug Metabolism, Hoffmann-La Roche Inc., Nutley, NJ 07110.
Ni
G
G
Nadeau
R
R
Liberato
D J
DJ
Loh
A
A
D000818:Animals; D002250:Carbon Radioisotopes; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism*; D007457:Iodine Radioisotopes; D007668:Kidney / Q000378:metabolism; D008297:Male; D007470:Monoiodotyrosine; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000378:metabolism; D014018:Tissue Distribution
D002250:Carbon Radioisotopes; D007376:Interleukin-2; D007457:Iodine Radioisotopes; D011994:Recombinant Proteins; D007470:Monoiodotyrosine