title: Increased soluble and platelet-associated CD40 ligand in essential thrombocythemia and reactive thrombocytosis.
abstract: CD40 ligand (CD40L) is expressed on activated CD4(+) T lymphocytes and at the activated platelet surface. A circulating soluble form of CD40L (sCD40L) is generated by the way of a proteolytic cleavage. We measured sCD40L in the plasma of either healthy subjects; patients with inflammatory disorders and low, normal, or high platelet count (reactive thrombocytosis); or patients with essential thrombocythemia (ET). A tight correlation was found between the platelet count and plasma sCD40L. ET patients had the highest levels of sCD40L. Platelet-associated CD40L was increased in ET and reactive thrombocytosis, conditions associated with increased platelet regeneration. Platelet-associated CD40L was released upon platelet activation. In conclusion, platelets appear as a reservoir of CD40L that may be a major contributor to circulating sCD40L. Platelet-associated CD40L may be a potential marker of platelet regeneration.
authors.affiliation: Department of Internal Medicine, Hôpital Haut-Lévêque, 5 avenue Magellan, 33604 Pessac, France. jean-francois.viallard@chu-bordeaux.fr
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Viallard
authors.forename: Anne
authors.initials: A
authors.lastname: Solanilla
authors.forename: Bruno
authors.initials: B
authors.lastname: Gauthier
authors.forename: Cécile
authors.initials: C
authors.lastname: Contin
authors.forename: Julie
authors.initials: J
authors.lastname: Déchanet
authors.forename: Christophe
authors.initials: C
authors.lastname: Grosset
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Moreau
authors.forename: Vincent
authors.initials: V
authors.lastname: Praloran
authors.forename: Paquita
authors.initials: P
authors.lastname: Nurden
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Pellegrin
authors.forename: Alan T
authors.initials: AT
authors.lastname: Nurden
authors.forename: Jean
authors.initials: J
authors.lastname: Ripoche
mesh_terms: D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000737:chemistry / Q000502:physiology*; D023201:CD40 Ligand / Q000032:analysis*; D002462:Cell Membrane / Q000276:immunology; D005260:Female; D005602:France; D006801:Humans; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation / Q000187:drug effects; D010976:Platelet Count; D012044:Regression Analysis; D013601:T-Lymphocytes / Q000276:immunology; D013920:Thrombocythemia, Essential / Q000097:blood* / Q000209:etiology; D013922:Thrombocytosis / Q000097:blood* / Q000209:etiology; D044465:White People
chemical_list: D023201:CD40 Ligand