Prophylactic versus therapeutic thrombolysis of pulmonary emboli in TgN-hCR1 mice. tPA, IgG/tPA, or anti-CR1/tPA (2 mg/kg tPA each) were injected intravenously into TgN-hCR1 mice 30 minutes before (A) or 10 minutes after (B) injecting ¹²⁵I-fibrin microemboli (ME). In panels A and B, the data are shown as the residual ¹²⁵I radioactivity in the lungs normalized to the injected dose of ¹²⁵I-ME (P < .005 for anti-CR1/tPA vs both mIgG/tPA and tPA in panel A and P < .002 for anti-CR1/tPA vs tPA in panel B). (C) Stimulation of fibrinolysis in the lungs after prophylactic or therapeutic administration of tPA and anti-CR1/tPA shown as the percent lysis stimulation versus the level of spontaneous lysis in control mice (n = 5 per group).