Blood clearance of anti-PECAM scFv-scuPA and kinetics of in vivo pulmonary targeting. (A) Blood clearance of targeted fusion construct (•) and nontargeted scuPA (○) in %ID/g (percentage of injected dose per gram tissue). (B) Kinetics of the targeted fusion protein levels in lungs (•) and blood (○). Fusion protein exhibited a rapid and prolonged accumulation in lung tissues. Lung-to-blood ratios at indicated time points were calculated (inset). (C) In vivo biodistribution of ¹²⁵I-scFv-uPA (▪) and free uPA (▦) 3 hours after intravenous injection in wild-type mice. Error bars indicate SEM.