Investigation of Alternative Mechanisms of Collagen - Induced Platelet Activation by Using Monoclonal Antibodies to Glycoprotein IIb-IIIa and Fibrinogen

Summary

Anti-HuPl-ml (reactive with IIIa) and anti-C₂G₇ (reactive with the carboxyl terminal of the a chain of fibrinogen) were used to investigate platelet aggregation, fibrinogen binding and thromboxane synthesis induced by low dose collagen (LDC) or high dose collagen (HDC) in normal or aspirin treated platelets.

Anti-HuPl-ml and anti-C₂G₇ inhibited LDC induced platelet aggregation almost completely whilst abolishing fibrinogen binding; thromboxane production although reduced, still occurred. Thus LDC activation was dependent on fibrinogen binding to Gp IIIa. Aggregation of platelets induced by HDC was inhibited with anti-C₂G₇ or anti-HuPl-ml by 15-35% in association with a modest reduction in thromboxane (TxB₂) production (with anti-HuPl-ml) and total inhibition of fibrinogen binding. When anti-HuPl-ml was added to aspirin treated platelets, aggregation with HDC although substantially reduced was not totally abolished.

Collagen appears to activate platelets in a dose related manner in which there are at least three possible mechanisms via: (i) GpIIb-IIIa and associated fibrinogen binding; (ii) prostaglandin pathway; (iii) an alternate pathway responsible for ∼20%-30% of platelet aggregation.

Key words

Collagen - Fibrinogen binding - Monoclonal antibodies - Mechanism of platelet activation

• References

• 1 Bennett JS, Vilaire G. Exposure of platelet fibrinogen receptors by ADP and epinephrine. J Clin Invest 1979; 64: 1393-1401
• 2 Plow EF, Marguerie GA. Participation of ADP in the binding of fibrinogen to thrombin-stimulated platelets. Blood 1980; 56: 553-555
• 3 Hardisty RM, Dormandy KM, Hutton RA. Thrombasthenia: Studies of three cases. Br J Haematol 1964; 10: 371-387
• 4 Gugler E, Lìscher EF. Platelet function in congenital afibrin-ogenaemia. Thrombos Diathes Haemorrh 1965; 14: 361-373
• 5 Polley MJ, Leung LL K, Clark FY, Nachmann RL. Thrombin induced platelet membrane glycoprotein IIb-IIIa complex formation. J Exp Med 1981; 154: 1058-1068
• 6 Di Minno G, Thiagarajan P, Perussia B, Martinez J, Shapiro S, Trinchiere G, Murphy S. Exposure of platelet fibrinogen-binding sites by collagen, arachidonic acid and ADP: Inhibition by a monoclonal antibody to the glycoprotein IIb-IIIa complex. Blood 1983; 61: 140-148
• 7 McEver RP, Baenzinger NL, Majerus PW. Isolation and quantitation of the platelet membrane glycoprotein deficient in thrombasthenia using a monoclonal hybridoma antibody. J Clin Invest 1980; 66: 1311-1318
• 8 Weiss HJ, Rogers J. Fibrinogen and platelets in the primary arrest of bleeding: Studies in two patients with congenital afibrinogenemia. N Engl J Med 1971; 285: 369-374
• 9 Coller BS, Peerschke EI, Scudder LE, Sullivan CA. A murine monoclonal antibody that completely blocks the binding of fibrinogen to platelets produces a thrombasthenic-like state in normal platelets and binds to glycoproteins IIb and/or IIIa. J Clin Invest 1983; 72: 325-338
• 10 Thurlow PJ, Barlow B, Connellan JM, McKenzie IF C. Detection of Glycoprotein II b and III a by monoclonal antibodies. Br J Haematol 1983; 55: 123-134
• 11 Thurlow PJ, Lovering KE, D’Apice AG F, McKenzie IF C. A monoclonal anti-Pan T cell antibody in vivo and in vitro studies. Transplantation 1983; 36: 293-298
• 12 Nyman D. Collagen induced platelet aggregation. Evidence of several mechanisms for the induction of platelet release by collagen. Thromb Res 1977; 10: 743-751
• 13 Best LC, Holland TK, Jones PB B, Russel RG G. The interrelationship between thromboxane biosynthesis, aggregation and 5-hydroxy tryptamine secretion in human platelets and vitro. Thromb Haemostas 1980; 43: 38-40
• 14 Aihara M, Cooper H, Wagner R. Platelet-collagen interactions: increase in rate of adhesion of fixed washed platelets by Factor VIII-related antigen. Blood 1984; 63: 495-501
• 15 Chesney CMc L, Pifer DD, Byers LW, Muirhead EE. The effect of platelet activating factor (PAF) on human platelets. Blood 1982; 59: 582-585
• 16 Vermylen J, Badenhorst PN, Deckmyn H, Arnout J. Normal mechanisms of platelet function. Clinics in Haematology, Platelet Disorders Harker L, Zimmerman F. (Eds). Vol 12 107-152 Saunders; London: 1983
• 17 Bennett JS, Vilaire G, Burch JW. A role for prostaglandins and thromboxanes in the exposure of platelet fibrinogen receptors. J Clin Invest 1981; 68: 981-987