Monoclonal Antibodies Against Porcine Platelet Membrane Glycoproteins lb and

We prepared murine monoclonal antibodies to porcine platelet membrane glycoprotein (GP) lb and GP llb/Illa for further study of the porcine hemostatic mechanism. One monoclonal antibody, designated PP3-4C. blocked Ristocetin-induced platelet agglutination and caused 80% inhibition of Ristocetin-induced ‘25l-von Willebrand factor (vWF) binding to porcine platelets at a concentration of 1 2 gsg lgG/mL. PP3-4C did not affect adenosine diphosphate (ADP)or collagen-induced platelet aggregation. Binding of 125l-Fab fragments of PP3-4C to platelets was saturable at 3.7 x i0 ± 0.8 x i0 molecules per platelet. Another monoclonal antibody. designated PP3-3A. blocked ADPor collagen-induced platelet aggregation at 6 sg lgG/mL. At a concentration of 10 g IgGImL. PP3-3A completely inhibited binding either of 125l-flbrinogen or of 125l-vWF to ADP-stimulated platelets. PP3-3A did not affect Ristocetininduced platelet agglutination nor 125l-vWF binding to platelets in the presence of Ristocetin. Binding of 125I-Fab’