Increased soluble and platelet-associated CD40 ligand in essential thrombocythemia and reactive thrombocytosis

• DOI: 10.1182/blood.v99.7.2612
• Publication Date: 2002-10-11T14:33:52Z
• Authors: Jean-François Vi...; Anne Solanilla; Bruno Gauthier; Cécile Contin; Julie Déchanet; Christophe Grosset; Jean-François Mo...; Vincent Praloran; Paquita Nurden; Jean-Luc Pellegrin; Alan T. Nurden; Jean Ripoche
• Keywords: Thrombocytosis

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.