title: Conjugation and evaluation of 7E3 x P4B6, a chemically cross-linked bispecific F(ab')2 antibody which inhibits platelet aggregation and localizes tissue plasminogen activator to the platelet surface.
abstract: A bispecific F(ab')2 monoclonal antibody which recognizes both the platelet GPIIb/IIIa receptor and human tissue plasminogen activator was produced to target tPA to platelets for enhancement of thrombolysis. A stable, thioether-cross-linked bispecific F(ab')2 (7E3 X P4B6) combining the GPIIb/IIIa-specific monoclonal antibody 7E3, which inhibits platelet aggregation, and a nonneutralizing anti-tPA monoclonal antibody (P4B6) was produced. This was performed by coupling each of the parental Fab' moieties with the homobifunctional cross-linker bis(maleimido methyl) ether (BMME). 7E3 X P4B6 was sequentially purified using gel-filtration chromatography and hydrophobic interaction (HIC) HPLC. HIC was shown to completely resolve each of the parental F(ab')2 species from the bispecific one. 7E3 X P4B6 was shown to retain completely each of the parental immunoreactivities in GPIIb/IIIa and tPA binding EIA's. The bispecific antibody inhibited platelet aggregation in vitro at levels comparable to those for 7E3 Fab. Recruitment of tPA activity to washed human platelets was demonstrated using the S-2251 chromogenic substrate assay. 7E3 X P4B6 recruited 12-fold more tPA to the washed platelets than a mixture of the parental F(ab')2 molecules used as controls.
authors.affiliation: Department of Immunobiology, Centocor Inc., Malvern Pennsylvania 19355.
authors.forename: D S
authors.initials: DS
authors.lastname: Neblock
authors.forename: C H
authors.initials: CH
authors.lastname: Chang
authors.forename: M A
authors.initials: MA
authors.lastname: Mascelli
authors.forename: M
authors.initials: M
authors.lastname: Fleek
authors.forename: L
authors.initials: L
authors.lastname: Stumpo
authors.forename: M M
authors.initials: MM
authors.lastname: Cullen
authors.forename: P E
authors.initials: PE
authors.lastname: Daddona
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000276:immunology; D001792:Blood Platelets / Q000378:metabolism*; D003432:Cross-Linking Reagents; D004337:Drug Carriers; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry* / Q000276:immunology; D066298:In Vitro Techniques; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D010980:Platelet Membrane Glycoproteins / Q000276:immunology; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology / Q000493:pharmacokinetics; D010959:Tissue Plasminogen Activator / Q000737:chemistry / Q000276:immunology / Q000493:pharmacokinetics*
chemical_list: D000911:Antibodies, Monoclonal; D003432:Cross-Linking Reagents; D004337:Drug Carriers; D007140:Immunoglobulin Fab Fragments; D010975:Platelet Aggregation Inhibitors; D010980:Platelet Membrane Glycoproteins; D011994:Recombinant Proteins; D010959:Tissue Plasminogen Activator