Conjugation to an antifibrin monoclonal antibody enhances the fibrinolytic potency of tissue plasminogen activator in vitro.
Tissue plasminogen activator (tPA) was covalently linked by disulfide bonds to a monoclonal antibody specific for the amino terminus of the beta chain of fibrin (antibody 59D8). The activity of the tPA-59D8 conjugate was compared with that of tPA, urokinase (UK), and a UK-59D8 conjugate. For lysis of fibrin monomer, tPA was 10 times as potent as UK, whereas both UK-59D8 and tPA-59D8 conjugates were 100 times as potent as UK and 10 times as potent as tPA. Conjugation of tPA or UK to antibody 59D8 produced a 3.2-4.5-fold enhancement in clot lysis in human plasma over that of the respective unconjugated plasminogen activator. However, the UK-59D8 conjugate was only as potent as tPA alone. Antibody-conjugated tPA or UK consumed less fibrinogen, alpha 2-antiplasmin, and plasminogen than did the unconjugated activators, at equipotent fibrinolytic concentrations. Antibody targeting thus appears to increase the concentration of tPA in the vicinity of a fibrin deposit, which thereby leads to enhanced fibrinolysis.
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex / Q000302:isolation & purification; D005337:Fibrin / Q000276:immunology*; D005342:Fibrinolysis; D007700:Kinetics; D010959:Tissue Plasminogen Activator / Q000276:immunology / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000276:immunology / Q000378:metabolism
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D005337:Fibrin; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator