Anti-fibrinogen antibody mediates fibrinogen binding to platelet membrane glycoprotein IIb-IIIa.
The binding of fibrinogen to platelets requires the agonist activation of platelet membrane glycoprotein IIb/IIIa. We have now found an anti-fibrinogen polyclonal antibody (YCU-R3) that increases the fibrinogen affinity of GPIIb/IIIa-binding function (activation) and subsequent platelet aggregation. The addition of intact IgG, F(ab)2 fragments or Fab fragments induced platelet aggregation. The antibody-mediated fibrinogen binding was specific and saturable. This binding was inhibited by native fibrinogen, the RGDS peptide, the peptide of the C-terminus gamma chain of fibrinogen (gamma 397-411), and the anti-GPIIb/IIIa monoclonal antibody (LJ-CP8). The antibody-dependent fibrinogen binding was similar to that induced by ADP. Moreover, after pretreatment with the anti-fibrinogen antibody and fibrinogen, formalin-fixed platelets bound to fibrinogen saturably. These results suggest that this anti-fibrinogen antibody may function as partial agonist.
Mohri
H
H
First Department of Internal Medicine, Yokohama City University School of Medicine, Japan.
Tanabe
J
J
Fujita
H
H
Kanamori
H
H
Ohkubo
T
T
D000906:Antibodies / Q000276:immunology*; D001792:Blood Platelets / Q000378:metabolism*; D015153:Blotting, Western; D004306:Dose-Response Relationship, Immunologic; D005340:Fibrinogen / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D010974:Platelet Aggregation / Q000276:immunology; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*
D000906:Antibodies; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D010980:Platelet Membrane Glycoproteins; D005340:Fibrinogen