Accessibility of Epitopes on Fibrin Clots and Fibrinogen Gels

• Published in: Blood 1991-04, Vol.77 (7), p.1469-1475
• Main Authors: Procyk, Roman, Kudryk, Bohdan, Callender, Stephen, Blombäck, Birger
• Format: Article
• Language: English
• Subjects: Antibodies, Monoclonal; Antigen-Antibody Complex; Biological and medical sciences; Blood Coagulation; Epitopes - analysis; Fibrin - immunology; Fibrin - physiology; Fibrinogen - immunology; Fibrinogen - physiology; Gels; Hematologic and hematopoietic diseases; Humans; Kinetics; Ligands; Medical sciences
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V77.7.1469.1469

Radiolabeled antibodies were perfused into fibrin clots and fibrinogen gels formed in vitro to assess the reactivity of selected epitopes. An antifibrinogen monoclonal antibody (MoAb) (antibody 1D4/xl-f), directed against an epitope in the Aά-chain C-terminal region (Aά241-476), bound to 35% of the epitope in crosslinked fibrin clots and 37% of the same epitope in factor Xlll-induced fibrinogen gel networks. A different MoAb (4-2/xl-f, antγ392-406) bound to only 7% of the epitope in both fibrin and fibrinogen gels. As expected, an antifibrin MoAb (antibody T2G1, antiBβ15-21 ) did not bind to fibrinogen gels, but bound to fibrin, although to only 14% of the available T2G1-reactive epitopes. An antibody that does not recognize fibrin (antibody 1-8C6, antiBβ1-21) predictably did not bind to fibrin clots and bound to 35% of the 1-8C6 epitopes present in fibrinogen gels, a level of binding also observed with antibody T2G1 and fibrinogen gels only after the latter were treated with thrombin. T2G1 epitope expression was affected much more than 1D4/xl-f epitope expression in clots formed in buffers of high or low ionic strength, conditions known to influence clot structure. Studies on the availability, in quantitative terms, of the T2G1-reactive epitope in fibrin clots is of particular importance because this antibody is currently being used in clinical trials as a clot imaging agent.