title: Immunoinhibition of ristocetin-induced platelet aggregation.
abstract: Human platelets washed and fixed in paraformaldehyde aggregate in the presence of the antibiotic ristocetin and normal plasma. This aggregation response is abolished after digestion of the fixed platelets with chymotrypsin. Antisera to fixed washed platelets were produced in rabbits and absorbed with chymotrypsin-treated, fixed washed platelets. Monovalent Fab fragments obtained from the isolated gamma-globulin fractions of the antisera blocked ristocetin-induced aggregation of fixed washed platelets in buffer and normal platelets in platelet-rich plasma. By double-antibody immunoprecipitation, it was shown that the antibody which blocked the ristocetin reaction interacted with a platelet membrane surface protein of mol wt 155,000. The results suggest that the glycoprotein I complex on the surface of the human platelet mediates ristocetin-induced von Willebrand factor-dependent platelet aggregation.
mesh_terms: D000906:Antibodies; D001792:Blood Platelets / Q000276:immunology; D002462:Cell Membrane / Q000276:immunology; D002918:Chymotrypsin / Q000494:pharmacology*; D005169:Factor VIII / Q000276:immunology; D006023:Glycoproteins / Q000276:immunology; D007106:Immune Sera; D010974:Platelet Aggregation / Q000187:drug effects*; D012310:Ristocetin / Q000037:antagonists & inhibitors*; D014841:von Willebrand Factor
chemical_list: D000906:Antibodies; D006023:Glycoproteins; D007106:Immune Sera; D014841:von Willebrand Factor; D012310:Ristocetin; D005169:Factor VIII; D002918:Chymotrypsin