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Activated human pla...
Activated human platelets induce factor XIIa-mediated contact activation
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- Bäck, Jennie (author)
- Uppsala universitet,Enheten för klinisk immunologi
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- Sanchez, Javier (author)
- Uppsala universitet,Enheten för klinisk immunologi
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- Elgue, Graciela (author)
- Uppsala universitet,Enheten för klinisk immunologi
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- Ekdahl, Kristina Nilsson (author)
- Linnéuniversitetet,Uppsala universitet,Enheten för klinisk immunologi,Institutionen för naturvetenskap, NV
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- Nilsson, Bo (author)
- Uppsala universitet,Enheten för klinisk immunologi
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(creator_code:org_t)
- Elsevier BV, 2010
- 2010
- English.
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In: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 391:1, s. 11-17
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Subject headings
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- Earlier studies have shown that isolated platelets in buffer systems can promote activation of FXII or amplify contact activation, in the presence of a negatively charge substance or material. Still proof is lacking that FXII is activated by platelets in a more physiological environment. In this study we investigate if activated platelets can induce FXII-mediated contact activation and whether this activation affects clot formation in human blood. Human platelets were activated with a thrombin receptor-activating peptide, SFLLRN-amide, in platelet-rich plasma or in whole blood. FXIIa and FXIa in complex with preferentially antithrombin (AT) and to some extent C1-inhibitor (C1INH) were generated in response to TRAP stimulation. This contact activation was independent of surface-mediated contact activation, tissue factor pathway or thrombin. In clotting whole blood FXIIa-AT and FXIa-AT complexes were specifically formed, demonstrating that AT is a potent inhibitor of FXIIa and FXIa generated by platelet activation. Contact activation proteins were analyzed by flow cytometry and FXII, FXI, high-molecular weight kininogen, and prekallikrein were detected on activated platelets. Using chromogenic assays, enzymatic activity of platelet-associated FXIIa, FXIa, and kallikrein were demonstrated. Inhibition of FXIIa in non-anticoagulated blood also prolonged the clotting time. We conclude that platelet activation triggers FXII-mediated contact activation on the surface and in the vicinity of activated platelets. This leads specifically to generation of FXIIa-AT and FXIa-AT complexes, and contributes to clot formation. Activated platelets may thereby constitute an intravascular locus for contact activation, which may explain the recently reported importance of FXII in thrombus formation.
Subject headings
- MEDICIN OCH HÄLSOVETENSKAP -- Medicinska och farmaceutiska grundvetenskaper -- Immunologi inom det medicinska området (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Basic Medicine -- Immunology in the medical area (hsv//eng)
Keyword
- Antithrombin
- Clot formation
- Contact activation
- Factor XII
- Platelets
- MEDICINE
- MEDICIN
- Immunology
- Immunologi
Publication and Content Type
- ref (subject category)
- art (subject category)
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