Platelet response to aggregated C-reactive protein: fibrinogen-dependent and independent signals.
Fibrinogen augmented gel-filtered platelet (GFP) aggregation only during an intermediate level of platelet activation stimulated by aggregated C-reactive protein (CRP) (AggCRP), implying that a mechanism to utilize fibrinogen is not operative or does not require an exogenous source of fibrinogen at near-maximal or threshold levels of platelet activation. By contrast, inclusion of the tetrapeptide fibrinogen antagonist, Arg-Gly-Asp-Ser(RGDS), inhibited both intermediate and near-maximal, but not threshold, levels of platelet activation stimulated by AggCRP. These data suggest that AggCRP initially stimulates platelets independent of fibrinogen but, in so doing, activates a fibrinogen-dependent mechanism(s) capable of augmenting the overall extent of platelet stimulation.
Fiedel
B A
BA
Division of Immunology, James N. Gamble Institute of Medical Research, Cincinnati, Ohio 45219.
D002097:C-Reactive Protein / Q000502:physiology*; D005340:Fibrinogen / Q000502:physiology*; D006801:Humans; D009842:Oligopeptides / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects
D009842:Oligopeptides; D005340:Fibrinogen; D002097:C-Reactive Protein; C046617:arginyl-glycyl-aspartyl-serine