DEFECTIVE INTERACTION BETWEEN VON-WILLEBRAND-FACTOR AND PLATELET GLYCOPROTEIN IB - A FAMILIAL STUDY OF PERIPHERAL ARTERIAL OCCLUSIVE DISEASE

Hemostatic variables and platelet function were assessed as a part of a genetic study in 15 patients with symptomatic peripheral arterial oc clusive disease(PAOD) and 15 healthy siblings from ten families. D-dim er, a degradation product of cross-linked fibrin, was increased in the PAOD group (mean +/- SD) (448 +/- 177 vs. 333 +/- 121 ng/ml, p <0.05) . Ristocetin-induced maximal platelet aggregation (RIPA) was reduced i n the PAOD group in response to both a higher (0.75 mg/ml) (67 +/- 28 vs. 87 +/- 14%, p = 0.02) and a lower (0.55 or 0.60 mg/ml) (33 +/- 21 vs. 59 +/- 32%, p = 0.02) concentration of ristocetin. Accordingly, th e rate of primary aggregation was smaller, and a larger threshold conc entration of ristocetin was needed to cause aggregation. However, rist ocetin cofactor activity, von Willebrand factor (vWF) antigen and its multimer distribution, plasma glycocalicin, platelet glycoprotein Ib c ontent and the binding of vWF to frozen and thawed washed platelets we re equal in both groups. Thus, the observed reduced RIPA in patients w ith PAOD is likely to reflect a down-regulation or blunted binding aff inity in the platelet surface glycoprotein Ib.