title: Binding of plasma factor XIII to thrombin-receptor activated human platelets.
abstract: Platelet-bound coagulation factor XIII (FXIII) is targeted and concentrated at the site where platelet-rich thrombi are formed. Previous studies were in disagreement about the nature of FXIII binding to platelets. In this study, thrombin-receptor activating peptide (TRAP)-stimulated human whole blood and washed platelets were analysed by flow cytometry for the binding of FXIII using a monoclonal antibody against the A subunit of FXIII (FXIII-A). Here, we demonstrate that FXIII-A positivity significantly increased on activated platelets in whole blood compared to unstimulated sample, but not in washed platelets. GPIIb/IIIa receptor plays an essential role in FXIII binding, as fibrinogen receptor antagonist eptifibatide and fibrinogen binding inhibitor RGDS tetrapeptide significantly prevented the binding of FXIII. Furthermore, stimulated platelets from a patient with severe type I Glanzmann thrombasthenia showed insignificant FXIII-A positivity versus healthy controls. In addition, basal negligible amount of FXIII on washed platelets was only slightly increased when highly purified plasma FXIII (FXIII-A(2)B(2)) was added upon platelet activation by TRAP. Similarly, no remarkable FXIII-A positivity was observed when we used FXIII-A(2)B(2) with gammaA/gammaA fibrinogen. However, gammaA/gamma' fibrinogen significantly augmented FXIII binding on TRAP-stimulated platelets in the presence of non-activated FXIII-A(2)B(2). We conclude that FXIII-A(2)B(2) of plasma origin binds to thrombin-receptor activated platelets via GPIIb/IIIa receptor-bound fibrinogen with gamma'-chain and is not capable of direct platelet binding.
authors: Department of Clinical Biochemistry and Molecular Pathology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
authors: Béla
authors: B
authors: Nagy
authors: Zsuzsa
authors: Z
authors: Simon
authors: Zsuzsa
authors: Z
authors: Bagoly
authors: László
authors: L
authors: Muszbek
authors: János
authors: J
authors: Kappelmayer
mesh_terms: D001777:Blood Coagulation / Q000502:physiology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D003600:Cytosol; D000077542:Eptifibatide; D005176:Factor XIII / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D009842:Oligopeptides / Q000494:pharmacology; D019007:P-Selectin / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology; D010949:Plasma; D015539:Platelet Activation / Q000187:drug effects / Q000502:physiology*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism; D013915:Thrombasthenia / Q000097:blood*
chemical_list: D009842:Oligopeptides; D019007:P-Selectin; D010446:Peptide Fragments; D010455:Peptides; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; C027539:fibrinopeptides gamma; C086309:thrombin receptor peptide SFLLRNP; D005340:Fibrinogen; D005176:Factor XIII; C046617:arginyl-glycyl-aspartyl-serine; D000077542:Eptifibatide