Interaction Of Platelets With Soluble, Polymerizing And Polymerized Fibrin In Human Plasma

Abstract

Previous studies on platele/fibrin interactions find polymerizing fibrin capable of inducing platelet aggregation but are controversial as to the same ability of soluble fibrin. It has also been controversial wether the fibrin-induced platelet aggregation is mediated via the platelet release or not. Since previous studies have utilized fibrin prepared With soluble phase thrombin or reptilase, it was of interest to reinvestigate the problem with fibrins prepared with insoluble phase reptilase (des-AA) and thrcmbin (des-AABB). Urea-solubilized des-AA or des-AABB fibrin monomers were added to hunan, citrated PRP (ci-PRP) in the aggregcmeter either in soluble anoints (8% of ci-PRP fibrinogen cone) or in amounts resulting in the formation of visible fibrin (50% of the ci-PRP fibrinogen level, or added as polymerized fibrin which had been homogenized.The increase in light transmission and beta-trcmboglobulin releas (β-TG) were recorded. Soluble or polymerized, homogenized fibrin had no effect on either parameter, whilst fibrin added in amounts resulting in visible fibrin formation (polymerizing fibrin) caused both platelet aggregation and β-TG release comparable to that of collagen (100 ug/ml) Fibrin monomer solvent (urea) had no such effects. In experiments with EDTA-PRP, visible aggregation was not observed but βTG confirmed that platelet release had taken place . With KCN-PRP and Acetylosalicylic-PRP,neither aggregation, norβ-TG ,was observed. It is concluded that: 1. Soluble or polymerized fibrin does not aggregate platelets. 2. Polymerizing fibrin aggregates platelets. 3. Platelet aggregation observed with polymerizing fibrin is mediated via the platelet release reaction. 4. Des-AA and des-AABB fibrin are equally potent in inducing platelet aggregation.