Antiplatelet glycoprotein Ib monoclonal antibody (OP-F1) totally abolishes ristocetin-induced von Willebrand factor binding, but has minimal effect on the botrocetin-induced binding.
We describe here a new antiplatelet glycoprotein (GP) Ib monoclonal antibody (MoAb) designated OP-F1 (IgG1 kappa). Both OP-F1 and a well-characterized anti-GPIb MoAb, AP-1, totally abolished ristocetin-induced von Willebrand factor (vWF) binding to platelets and desialylated vWF binding to platelets at an IgG concentration of 2-8 micrograms/ml. AP-1 also blocked snake venom botrocetin-induced vWF binding at a similar IgG concentration, whereas OP-F1 had a minimal effect on botrocetin-induced binding. At a higher IgG concentration (150 micrograms/ml), OP-F1 inhibited botrocetin-induced binding by 50%. AP-1 (IgG) did not interfere with binding of [125I]OP-F1 (IgG) to platelets. Thus, the epitope involved in the binding of OP-F1 or AP-1 appears to be quite different. These results suggest that the vWF binding site(s) on the GPIb molecule generated by these inducers is in close proximity but not completely identical.
Nishio
K
K
Department of Blood Transfusion, Nara Medical College, Japan.
Fujimura
Y
Y
Nishida
S
S
Takeda
I
I
Yoshioka
A
A
Fukui
H
H
Tomiyama
Y
Y
Kurata
Y
Y
D000911:Antibodies, Monoclonal / Q000276:immunology*; D001667:Binding, Competitive; D003435:Crotalid Venoms / Q000494:pharmacology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D010980:Platelet Membrane Glycoproteins / Q000276:immunology / Q000502:physiology*; D011485:Protein Binding; D012310:Ristocetin / Q000494:pharmacology*; D014841:von Willebrand Factor / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D003435:Crotalid Venoms; D007074:Immunoglobulin G; D010980:Platelet Membrane Glycoproteins; D014841:von Willebrand Factor; D012310:Ristocetin; C030961:botrocetin