Effects of injected antibody against the platelet glycoprotein IIb/IIIa complex on monkey platelet fibrinogen.
Four monkeys were injected for a 10-day period with the Fab fragment of a murine monoclonal antibody (NNKY 1-32) which inhibits the binding of fibrinogen to the platelet glycoprotein (GP) IIb/IIIa complex. Platelet fibrinogen levels were assessed quantitatively by electroimmunoassay and qualitatively by immunoelectron microscopy. The platelet fibrinogen level fell to 9.0 +/- 2.8% of the control level after antibody administration. Immunoelectron microscopy showed that the injected antibody was localized on the inner surface of the platelet alpha-granule membrane. Our findings suggest that the GP IIb/IIIa complex can be internalized by alpha-granules and that it may mediate the endocytosis of plasma fibrinogen by platelets.
Suzuki
M
M
First Department of Internal Medicine, Kansai Medical University, Osaka, Japan.
Kawakatsu
T
T
Nagata
H
H
Hamamoto
K
K
Iwata
K
K
Ohga
S
S
Nomura
S
S
Kokawa
T
T
Yasunaga
K
K
D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D016616:Cryoultramicrotomy; D005340:Fibrinogen / Q000276:immunology*; D007118:Immunoassay / Q000379:methods; D007275:Injections, Intravenous; D008251:Macaca; D016253:Microscopy, Immunoelectron; D010980:Platelet Membrane Glycoproteins / Q000276:immunology*
D000911:Antibodies, Monoclonal; D010980:Platelet Membrane Glycoproteins; D005340:Fibrinogen