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B Ando, T Wiedmer and PJ Sims
Cardiovascular Biology Research Program, Oklahoma Medical Research
Foundation, Oklahoma City 73104.
The secretory and aggregation responses of stirred platelets exposed to
complement proteins C5b-9 was investigated. C5b-9 assembly on the platelet
surface resulted in the release of dense granule adenosine triphosphate
(ATP) accompanied by a decrease in sample turbidity, but no detectable cell
lysis. Inhibition of cellular protein kinase C completely blocked the C5b-9
initiated release of ATP, confirming the secretory nature of this response.
Addition of fibrinogen (up to 1 mg/mL) had no effect on either the release
of ATP or the decreased turbidity observed for C5b-9 cells. Addition of the
peptides Arg-Gly- Asp-Ser (RGDS) and fibrinogen gamma-chain
carboxyl-terminal (gamma 397- 411) at concentrations sufficient to
completely block fibrinogen binding to GP IIb-IIIa had no effect on either
C5b-9 induced dense granule secretion or the associated turbidity change.
Microscopic examination and electronic particle counting of the stirred
platelet suspensions confirmed that no aggregation of C5b-9 platelets
occurred even when these cells were stirred in the presence of fibrinogen.
The capacity of the C5b-9 proteins to initiate platelet secretion without
activation of cell surface glycoprotein (GP) IIb-IIIa suggests a mechanism
for intravascular dissemination of activated platelets during complement
activation in vivo.
This article has been cited by other articles:
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| Copyright © 1989 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
