Pharmacokinetic and blood-clearance studies. (A) Whole-blood clearance of 1.4 nM (300 μg) 131I-labeled 1F5 Ab-SA chemical conjugate (▿) or 1.4 nM (245 μg) 125I-labeled 1F5 (scFv)₄SA, each injected intraperitoneally into athymic BALB/c mice (n = 5/group). (B) The effect of a biotinylated polymeric, N-acetyl-galactosamine-containing CA, on circulating 125I-1F5 (scFv)₄SA FP. 125I-1F5 (scFv)₄SA (1.4 nM) was injected intraperitoneally into 5 BALB/c athymic mice at time 0 hours. The CA (50 μg; 5.8 nM intraperitoneally) was injected 20 hours after the labeled FP. In each experiment, serial blood samples were obtained from the retro-orbital venous plexus at the times indicated after the injection of each Ab-SA construct and analyzed by gamma counting. Results are representative of 3 experiments.