On the retraction of collagen and fibrin induced by normal, defective and modified platelets.

Fibrin clot retraction (FCR) and collagen gel retraction (CGR) were studied in patients with inherited platelet defects, i.e. in Glanzmann's thrombasthenia, Hermansky-Pudlak syndrome, May-Hegglin anomaly, giant platelet syndrome, as well as in patients with von Willebrand disease and factor XIII deficiency. FCR was abnormal only in thrombasthenia, while CGR was found to be reduced in 2 patients with Hermansky-Pudlak syndrome and in 4 out of 5 cases with von Willebrand disease. Both FCR and CGR were normal in May-Hegglin anomaly, giant platelet syndrome and severe factor XIII deficiency. In none of the examined bleeding disorders was a concomitant FCR and CGR reduction detected. Natural polyamines and anti-fibronectin antibodies did not affect platelet potency in FCR or CGR. Peroxidation of platelet membrane components by sodium periodate abolished the platelet-induced FCR and CGR. This effect was reversed by subsequent reduction by sodium borohydride.