title: Specific activation of platelets by surface-adsorbed plasma proteins.
abstract: Platelets were isolated from human blood by Percoll density gradient centrifugation in a low Ca2+/high Mg2+ buffer. The buffer reversibly inactivates the cells during separation. The purity of the isolated cells (> 99%) was determined by flow cytometry, their viability was confirmed by fluorescein diacetate hydrolysis, and their morphology was studied with TEM. Plasma proteins were adsorbed onto hydrophobic glass surface, and pure platelets were added and incubated for up to 30 min at 37 degree C. Platelet activation was determined by cell spreading, formation of microparticles and surface exposure of CD62P indicating the release of alpha-granules. Surface-immobilized IgG was shown to cause the release of microparticles and cell lysis, in accordance with data published by others. Surface-immobilized vWF was shown to induce CD62P exposure on the platelet cell surface. The specificity of this response was demonstrated by adsorbing plasma proteins from normal and factor VIII-deficient plasma.
authors.affiliation: Department of Anatomy and Cell Biology, University of Göteborg, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Nygren
authors.forename: M
authors.initials: M
authors.lastname: Broberg
mesh_terms: D001792:Blood Platelets / Q000737:chemistry* / Q000187:drug effects / Q000648:ultrastructure; D001798:Blood Proteins / Q000737:chemistry* / Q000494:pharmacology; D002469:Cell Separation; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000494:pharmacology; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D019007:P-Selectin / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D015539:Platelet Activation / Q000187:drug effects*; D012709:Serum Albumin / Q000737:chemistry / Q000494:pharmacology; D013499:Surface Properties; D014841:von Willebrand Factor / Q000737:chemistry / Q000494:pharmacology
chemical_list: D001798:Blood Proteins; D007074:Immunoglobulin G; D019007:P-Selectin; D012709:Serum Albumin; D014841:von Willebrand Factor