title: A monoclonal antibody preventing binding of tissue-type plasminogen activator to fibrin: useful to monitor fibrinogen breakdown during t-PA infusion.
abstract: One (MA-1C8) of 36 monoclonal antibodies obtained by fusion of P3X63-Ag8-6.5.3 myeloma cells with spleen cells of mice immunized with purified human tissue-type plasminogen activator (t-PA) blocked the activity of t-PA on fibrin plates but not on chromogenic substrates. MA-1C8 at a concentration of 200 micrograms/mL inhibited plasma clot lysis and binding of t-PA to the clot. MA-1C8 had no influence on the activation of plasminogen by t-PA, which obeys Michaelis-Menten kinetics with Km = 105 mumol/L and kcat = 0.05 s-1; however, it abolished the influence of CNBr-digested fibrinogen on Km. These findings confirm that the stimulatory effect of fibrin on the activation of plasminogen by t-PA is mediated by binding of t-PA to fibrin and provide additional support for the kinetic model. Addition of t-PA to pooled fresh human plasma to a concentration of 5 micrograms/mL resulted in extensive fibrinogen breakdown after incubation for one hour at 37 degrees C or during storage at -20 degrees C for one day. In both instances, fibrinogen degradation was completely prevented by addition of MA-1C8 to a concentration of 200 micrograms/mL of plasma. MA-1C8 also effectively prevented in vitro fibrinogen degradation and in vitro plasminogen activation in plasma samples obtained during infusion of recombinant t-PA in patients with thromboembolic disease. Thus, MA-1C8 is a useful tool for discriminating between in vivo and in vitro fibrinolysis during thrombolytic therapy with t-PA.
authors.forename: P
authors.initials: P
authors.lastname: Holvoet
authors.forename: H R
authors.initials: HR
authors.lastname: Lijnen
authors.forename: D
authors.initials: D
authors.lastname: Collen
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D003488:Cyanogen Bromide; D005337:Fibrin / Q000378:metabolism*; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis; D005340:Fibrinogen / Q000378:metabolism*; D005342:Fibrinolysis / Q000187:drug effects; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D006801:Humans; D007700:Kinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D010446:Peptide Fragments / Q000494:pharmacology; D010689:Phlebitis / Q000097:blood / Q000188:drug therapy; D010959:Tissue Plasminogen Activator / Q000276:immunology / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D005338:Fibrin Fibrinogen Degradation Products; D005343:Fibrinolytic Agents; D010446:Peptide Fragments; D005337:Fibrin; D005340:Fibrinogen; D010959:Tissue Plasminogen Activator; D003488:Cyanogen Bromide