Coated platelets and severe haemophilia A bleeding phenotype: Is there a connection?

Abstract

Coated platelet levels were not associated with bleeding phenotype in this study; however, these data may suggest coated platelet levels are lower in haemophilia patients relative to healthy volunteers.

Expression and release of platelet protein disulphide isomerase in patients with haemophilia A

“…To correlate laboratory findings with the bleeding phenotype, patients were categorized into two groups based on annual bleeding rate and presence of haemophilic arthropathy. Patients were defined as having a severe bleeding phenotype if they had >5 bleeds per year and/or clinically relevant chronic arthropathy in at least one joint (i.e. orthopaedic joint score, >4).…”

“…While the procoagulant activity of stimulated platelets critically impacts on thrombin generation at low FVIII plasma levels , somewhat conflicting results exist with regard to the presence of preactivated platelets in patients with severe haemophilia A or the ability to generate highly procoagulant (i.e. coated) platelets upon ex vivo stimulation . These findings indicate that the specific mechanisms by which platelets modulate the haemostatic response to vascular injury in haemophilia A have not been conclusively resolved.…”

LPS-induced expression and release of monocyte tissue factor in patients with haemophilia

“…Our study was based on the original hypothesis that patients with increased LPS-induced monocyte TF production had a milder bleeding phenotype than patients with a less pronounced response, which we could not confirm. It must be considered, however, that there is no consistent definition of the bleeding phenotype [29], and our definition might be oversimplified, not taking into account that patients on effective prophylaxis hardly bleed and usually have no significant joint disease. We also used peripheral blood monocytes as a surrogate for tissue macrophages, which are key components of the haemostatic envelope.…”

Decreased platelet surface phosphatidylserine predicts increased bleeding in patients with severe factor VIII deficiency

“…10 A higher percentage of coated platelets and increased collagen-stimulated platelet activation have been reported in some studies of hemophilia patients to be associated with less frequent bleeding. [7][8][9][11][12][13][14] The aim of this study was to determine whether platelet func-…”

“…Activated platelets, in addition to their role in primary hemostasis, play a major role in secondary hemostasis (coagulation) by providing a phospholipid surface to which coagulation factors bind, thereby increasing the rate of factor activation more than 1000‐fold 10 . A higher percentage of coated platelets and increased collagen‐stimulated platelet activation have been reported in some studies of hemophilia patients to be associated with less frequent bleeding 7‐9,11–14 …”