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Thromb Haemost 1998; 79(04): 796-801
DOI: 10.1055/s-0037-1615067
Rapid Communication
Schattauer GmbH

Evaluation of the Factors Contributing to Fibrin–dependent Plasminogen Activation

Authors

  • Michael W. Mosesson

    1   From the Sinai Samaritan Medical Center, University of Wisconsin Medical School-Milwaukee Clinical Campus, Milwaukee, USA

  • Kevin R. Siebenlist

    1   From the Sinai Samaritan Medical Center, University of Wisconsin Medical School-Milwaukee Clinical Campus, Milwaukee, USA

  • Marijke Voskuilen

    2   From the Gaubius Laboratory TNO–PG, Leiden, The Netherlands

  • Willem Nieuwenhuizen

    2   From the Gaubius Laboratory TNO–PG, Leiden, The Netherlands

The results of this study were published in abstract form and presented in part at the XIII International Congress on Fibrinolysis and Thrombolysis, Barcelona, Spain, June 24-28, 1996, and at the XIV International Fibrinogen Workshop, Canberra, Australia, August 21-23, 1996 [Fibrinolysis (1996) 10: Suppl. 4, 13]
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Publikationsverlauf

Received 27. August 1997

Accepted after revision 03. Dezember 1997

Publikationsdatum:
07. Dezember 2017 (online)

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Summary

Polymerized fibrin strongly enhances tissue plasminogen activator (tPA)-mediated plasminogen activation, concomitant with exposure of ‘fibrin-specific’ epitopes at ‘Aα148-160’ and ‘γ312-324’. To investigate which aspects of polymerization are involved in these activities, we explored the fibrin polymerization process by evaluating the ability of factor XIIIa-crosslinked fibrinogen polymers to expose ‘fibrin-specific’ epitopes and enhance plasminogen activation. Crosslinked normal fibrinogen, fibrinogen with deficient [des Bβ1-42] or defective [Birmingham (AαR16H)] fibrin ‘D:E’ assembly sites (‘EA’), or with defective end-to-end self-association sites (‘D:D’) [Cedar Rapids (γR275C)], exposed both ‘fibrin-specific’ epitopes and enhanced tPA-dependent plasminogen activation, whereas non-crosslinked fibrinogens showed minimal or no such activities. Epitope expression in cross-linked fibrinogen was retained in the presence of the fibrin EA site peptide homolog, gly-pro-arg-pro (GPRP), which inhibits fibrin D:E association, except for the Aα148-160 epitope in des Bβ1-42 fibrinogen, which was not expressed. Fibrin prepared from crosslinked normal or abnormal fibrinogen, except for the des Bβ1-42 fibrin epitopes, which were reduced or absent, expressed ‘fibrin-specific’ epitopes even in the presence of GPRP, which otherwise impairs such expression in noncrosslinked fibrin. Epitope exposure in fibrin prepared from non-cross-linked fibrinogen was nearly normal in Cedar Rapids fibrin (heterozygous D:D defect), but reduced in Birmingham fibrin (heterozygous EA defect), nil in des Bβ1-42 fibrin (EA deficient), and absent in all cases in the presence of GPRP. In contrast, plasminogen activation stimula-tory activity that had been exposed in crosslinked normal fibrinogen or in crosslinked des Bβ1-42 or Cedar Rapids fibrin, was preserved to a large extent in the presence of GPRP, suggesting that once enhanced stimulatory activity and epitopes are exposed, they are not completely reversible. The findings indicate that end-to-end intermolecular associations (D:D) are not critical for ‘fibrin-specific’ epitope exposure, but that polymerization brought about in fibrinogen through factor XIIIa crosslinking, or in fibrin through ‘D:E’ interactions, is necessary for ‘fibrin-specific’ (more correctly, ‘polymerization-specific’) epitope exposure and enhancement of plasminogen activation.