Thromb Haemost 1989; 61(02): 307-313
DOI: 10.1055/s-0038-1646582
Original Article
Schattauer GmbH Stuttgart

Binding Properties of Monoclonal Antibodies against Human Fragment D-Dimer of Cross-Linked Fibrin to Human Plasma Clots in an In Vivo Model in Rabbits

Authors

  • P Holvoet

    The Center for Thrombosis and Vascular Research and the Laboratory for Nuclear Medicine, University of Leuven, Belgium
  • J M Stassen

    The Center for Thrombosis and Vascular Research and the Laboratory for Nuclear Medicine, University of Leuven, Belgium
  • Y Hashimoto

    The Center for Thrombosis and Vascular Research and the Laboratory for Nuclear Medicine, University of Leuven, Belgium
  • D Spriggs

    The Center for Thrombosis and Vascular Research and the Laboratory for Nuclear Medicine, University of Leuven, Belgium
  • P Devos

    The Center for Thrombosis and Vascular Research and the Laboratory for Nuclear Medicine, University of Leuven, Belgium
  • D Collen

    The Center for Thrombosis and Vascular Research and the Laboratory for Nuclear Medicine, University of Leuven, Belgium
Further Information

Publication History

Received 10 December 1987

Accepted after revision 13 December 1988

Publication Date:
30 June 2018 (online)

Preview

Summary

Two (MA-15C5 and MA-8D3) out of approximately 500 monoclonal antibodies, obtained by fusion of P3X63-Ag8-6.5.3 myeloma cells with spleen cells of mice immunized with purified fragment D-dimer from human fibrin, demonstrated a more than 1,000-fold higher affinity for fragment D-dimer than for native fibrinogen. MA-15C5 was directed against a neoantigenic determinant only expressed in fragment D-dimer. MA-8D3 reacted equally well with fragment D-dimer of crosslinked fibrin and with fragment D of non-crosslinked fibrin but not with fragment D of fibrinogen. Both monoclonal antibodies did not crossreact with rabbit fibrin and its degradation products.

The binding of 125I-labeled Fab fragments to human plasma clots, introduced and aged for 1 hr in the jugular vein of heparinized rabbits was studied. Following injection of an equimolar mixture of Fab fragments derived from MA-15C5 and MA-8D3, the clot to blood ratios of radioactivity increased from 3.2 ± 1.2(mean ± SD) at 4 hr to 7.2 ± 1.4 at 17 hr. The binding of Fab fragments of MA-15C5 and MA-8D3 was independent of the age (1 to 72hrs) of the clot and of heparin anticoagulation and was only slightly decreased (by 20%) in the presence of circulating human fibrinogen (90 mg/kg body weight) and of human crosslinked fibrin degradation products at a plasma concentration of 10 pg/ml. The binding of Fab fragments of MA-15C5 and MA-8D3 to occlusive human plasma clots in the femoral artery of rabbits was comparable to that of the non-occlusive human plasma clots in the jugular vein. The Fab fragments of MA-15C5 and MA-8D3, labeled with 123I to a specific activity of 10 μCi/pg were injected intravenously (3 μg/kg) in 72 rabbits with a nonocclusive 0.2 ml human plasma clot in the jugular vein and in 7 control rabbits that underwent the surgical procedure without clot formation. Total body scans performed at hourly intervals revealed a higher relative increase in gamma counts over the thrombus region in the group with thrombus as compared to controls: at 6 hr 54 ± 18 vs 16 ± 13% (mean ± SEM, p <0.1) and at12 hrs 35 ± 11 vs –7 ± 12 (p <0.05). The vein segment to blood ratios of 123I at 24 hrs were 6.6 ± 2.4 in the group with clot and 1.5 to 0.7 in the control group (p <0.01). We conclude that these Fab fragments may have a sufficiently high fibrin-affinity to allow in vivo thrombus localization by external scanning.