Interactions of Purified Rat Factor VIII/von Willebrand Factor with Rat and Human Platelets – Effect of Albumin and Ristocetin^[*]

Summary

Rat platelets do not respond to ristocetin in their own plasma nor do they aggregate in the presence of bovine or porcine factor VIII von Willebrand factor (F VIII R:WF) or human F VIII R:WF in presence of ristocetin. However, rat plasma supports ristocetin induced aggregation of washed human platelets. In this study we report on purification of rat F VIII R:WF from cryoprecipitate. Similarly to porcine or bovine material, purified rat F VIII R:WF induced aggregation of human washed fixed platelets. This effect was enhanced by addition of ristocetin and was not modified by addition of albumin. Rat washed platelets were aggregated by ristocetin in the presence of rat or human F VIII R:WF provided that high concentrations of ristocetin are added in a system essentially free of extraneous proteins. Increasing concentrations of albumin dramatically reduced the ability of ristocetin to aggregate rat platelets while human platelet aggregation by human or rat F VIII R:WF was only moderately affected.

These studies show that rat F VIII R:WF can interact with rat and human platelets. The lack of response of rat platelets to ristocetin in their own plasma is most likely due to a low sensitivity of rat platelets to this drug and to an inhibitory activity of plasma proteins on this reaction.

Keywords

Rat factor VIII/von Willebrand factor - Ristocetin - Albumin - Platelet aggregation

• References

• 1 Hoyer LW. The factor VIII complex: Structure and function. Blood 1981; 58: 1-13
• 2 Tschopp TB, Weiss HJ, Baumgartner HR. Decreased adhesion of platelets to subendothelium in von Willebrand’s disease. J Lab Clin Med 1974; 83: 296-300
• 3 Howard MA, Firkin BG. Ristocetin - a new tool in the investigation of platelet aggregation. Thrombos Diathes Haemorrh 1971; 24: 362-369
• 4 Brinkhous KM, Thomas BD, Ibrahim SA, Read MS. Plasma levels of platelet aggregating factor/von Willebrand factor in various species. Thromb Res 1977; 11: 345-355
• 5 Dodds WJ. Platelet function in animals: species specificities. In Platelet: A Multidisciplinary Approach. de Gaetano G, Garattini S. (eds) pp 45-59 Raven Press; New York: 1978
• 6 Johnson GS, Benson RE, Dodds WJ. Ristocetin cofactor activity of purified canine factor VIII: Inhibition by plasma proteins. Thromb Res 1979; 15: 835-846
• 7 Donati MB, de Gaetano G, Vermylen J. Evidence that bovine factor VIII, not bovine fibrinogen, aggregates human platelets. Thromb Res 1973; 2: 97-104
• 8 Griggs TR, Cooper HA, Webster WP, Wagner RH, Brinkhous KM. Plasma aggregating factor (bovine) for human platelets: A marker for study of antihemophilic and von Willebrand factors. Proc Natl Acad Sci USA 1973; 70: 2814-2818
• 9 de Gaetano G, Donati MB, Vermylen J. Evidence that human platelet aggregating activity in porcine plasma is a property of von Willebrand factor. Thrombos Diathes Haemorrh 1974; 32: 549-553
• 10 de Gaetano G, Donati MB, Reyers-Degli Innocenti I, Roncaglioni MC. Defective ristocetin and bovine factor VIII-induced platelet aggregation in normal rats. Experientia 1975; 31: 500-501
• 11 Furlan M, Perret BA, Beck EA. Studies on factor VIII-related protein. III. Size distribution and carbohydrate content of human and bovine factor VIII. Biochim Biophys Acta 1979; 579: 325-333
• 12 Beck EA, Tranqui-Pouit L, Chapel A, Perret BA, Furlan M, Hudry-Clergeon G, Suscillon M. Studies on factor VIII-related protein. I. Ultrastructural and electrophoretic heterogeneity of human factor VIII-related protein. Biochim Biophys Acta 1979; 578: 155-163
• 13 Ardlie MG, Packham MA, Mustard JF. Adenosine diphosphate- induced platelet aggregation in suspensions of washed rabbit platelets. Br J Haematol 1970; 19: 7-17
• 14 Baugh RF, Brown JE, Hougie C. Plasma components which interfere with ristocetin-induced platelet aggregation. Thrombos Diathes Haemorrh 1975; 33: 540-546
• 15 Stibbe J, Kirby EP. The influence of haemaccel, fibrinogen and albumin on ristocetin-induced platelet aggregation. Relevance to the quantitative measurement of the ristocetin cofactor Thromb Res 1976; 8: 151-165
• 16 Cooper HA, Clementson KJ, Luscher EF. Human platelet membrane receptor for bovine von Willebrand factor (platelets aggregating factor): An integral membrane glycoprotein. Proc Natl Acad Sci USA 1979; 76: 1069-1073
• 17 Toor B, McGregor JL, McGregor L, Clementson KJ. Comparison of the major membrane glycoproteins and proteins of human, rabbit and rat blood platelets. Thromb Res 1982; 26: 317-328
• 18 Allain JP, Cooper RH, Wagner RH, Brinkhous KM. Platelets fixed with paraformaldehyde; a new reagent for assay of von Willebrand factor and platelet aggregating factor. J Lab Clin Med 1975; 85: 318-328
• 19 Moake JL, Olson JD, Troll JH, Tang SS, Funicella T, Peterson DM. Binding of radioiodinated human von Willebrand factor to Bemard-Soulier thrombasthenic and von Willebrand’s disease platelets. Thromb Res 1980; 19: 21-27