Effects of proteolytic degradation products of human fibrinogen and of human factor VIII on platelet aggregation and vascular permeability

Abstract Products of proteolysis of highly purified preparations of human fibrinogen (FDP) and of human factor VIII (VIII-DP) by plasmin were compared with respect to their ability to inhibit platelet aggregation and to enhance the permeability of rat skin microvasculature. Low molecular weight dialysable FDP (LMW-FDP, m. w. under 2754) induced complete inhibition of platelet aggregation in PRP at concentrations of and above 2. 5 mg/ml. Slight or very pronounced increase in skin microvasculature permeability was observed at LMW-FDP doses of 10 μg and 78 μg, respectively. In contrast, the whole digest of factor VIII as well as LMW-VIII-DP appeared inactive. Unfractionated digests of fibrinogen and fibrin formed either by thrombin of Defibrase exhibited the same antiaggregating potency.