ADHESION OF PLATELETS TO HUMAN ARTERY SUBENDOTHELIUM - EFFECT OF FACTOR-VIII-VONWILLEBRAND FACTOR OF VARIOUS MULTIMERIC COMPOSITION

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  • 1 January 1984
    • journal article
    • research article
    • Vol. 63  (1) , 128-139
Abstract
The relationship between the multimeric size of factor VIII-von Willebrand factor (FViii-vWF) and the support of platelet adhesion to subendothelium was studied in an annular perfusion chamber, employing human renal and umbilical arteries. Commercial factor VIII concentrates containing multimers of low MW that had been shown not to correct the bleeding time upon infusion into patients with von Willebrand''s disease did not support platelet adhesion in the perfusion chamber. Cryoprecipitate and 2 experimental FVIII-vWF concentrates containing multimers of high MW supported platelet adhesion. Factor VIII-vWF purified from cryoprecipitate was subdivided into 3 fractions of different MW (6.0-14.0, 4.0-9.0 and 3.0-7.5 .times. 106 dalton). These fractions appeared to bind equally well and to be equally effective in supporting platelet adhesion. Factor VIII-vWF with multimers of low MW (0.5-1.5 .times. 106 dalton) were prepared by partial reduction. Binding of FVIII-vWF to subendothelium was not impaired, and the support of platelet adhesion appeared to be more resistant to the effect of reduction than the ristocetin cofactor activity. At high shear rate (2500 s-1), increased platelet adhesion was observed with partially reduced FVIII-vWF. The ability of FVIII-vWF preparations to correct the bleeding time is reflected in enhanced platelet adhesion to subendothelium in a perfusion chamber. Multimeric size is not the only factor determining whether FVIII-vWF will support platelet adhesion.