title: Plasma components which interfere with ristocetin-induced platelet aggregation.
abstract: Normal human plasma contains a component or components which interfere with ristocetin-induced platelet aggregation. Preliminary examination suggests a protein (or proteins) which binds ristocetin and competes more effectively for ristocetin than do the proteins involved in ristocetin-induced platelet aggregation. The presence of this protein in normal human plasma also prevents ristocetin-induced precipitation of plasma proteins at levels of ristocetin necessary to produce platelet aggregation (0.5-2.0 mg/ml). Serum contains an apparent two0fold increase of this component when compared with plasma. Heating serum at 56 degrees for one hour results in ad additional 2 to 4 forl increase. The presence of a ristocetin-binding protein in normal human plasma requires that this protein be saturated with ristocetin before ristocetin-induced platelet aggregation will occur. Variations in the ristocetin-binding protein(s) will cause apparent discrepancies in ristocetin-induced platelet aggregation in normal human plasmas.
mesh_terms: D000327:Adsorption; D000536:Aluminum Hydroxide; D001667:Binding, Competitive; D001798:Blood Proteins / Q000494:pharmacology*; D011232:Chemical Precipitation; D006358:Hot Temperature; D006801:Humans; D010973:Platelet Adhesiveness / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects*; D011485:Protein Binding; D012310:Ristocetin / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology; D014842:von Willebrand Diseases / Q000097:blood
chemical_list: D001798:Blood Proteins; D012310:Ristocetin; D000536:Aluminum Hydroxide