title: Soluble CD40L release as test for functional platelet loss.
abstract: BACKGROUND
  During platelet storage, alterations of the platelet function, 'platelet storage lesion', can be observed resulting in a reduced platelet viability. The release of soluble CD40 ligand (sCD40L) by platelets reflects different aspects of platelet metabolism and activity. Therefore, we used the sCD40L release to test for functional platelet loss in platelet products during storage in comparison to the formation of thromboxane (TXB2).
  
  
  METHODS
  On day 1, 3, and 5 in single donor apheresis platelet products (n = 8) under routine storage conditions, sCD40L (measured by ELISA) and TXB2 (measured by RIA) were determined after platelet stimulation (recalcification and clot formation). Results were related to a therapeutic unit (TU = 2 x 10*11 platelets).
  
  
  RESULTS
  In platelet-rich plasma of the donors, sCD40L release was 42.5 +/- 7.1 ng/TU and TXB2 formation 2,183 +/- 576 ng/TU. On day 1, 3, and 5 sCD40L release was reduced to 95%, 64%, and 57% and TXB2 formation to 92%, 80%, and 65% of the respective control values.
  
  
  CONCLUSIONS
  In single donor apheresis PCs, sCD40L release and TXB2 formation showed a comparable course over storage time and were reduced to about 60% of the respective control values after a storage period of 5 days. These findings are in line with literature data indicating that a functional platelet loss of about 30% will occur after 5 days of storage. Overall, sCD40L release could be easily induced by recalcification and clot formation and can be used as a marker for functional platelet loss.
authors.affiliation: Institute for Transplantation Diagnostics and Cell Therapeutics, Medical Center of University Düsseldorf, Germany. folker.wenzel@gmx.de
authors.forename: Folker
authors.initials: F
authors.lastname: Wenzel
authors.forename: Thomas
authors.initials: T
authors.lastname: Hohlfeld
authors.forename: Günther
authors.initials: G
authors.lastname: Giers
mesh_terms: D000328:Adult; D015415:Biomarkers; D001792:Blood Platelets / Q000378:metabolism*; D023201:CD40 Ligand / Q000032:analysis* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D015539:Platelet Activation; D010979:Platelet Function Tests / Q000379:methods*; D053657:Platelet-Rich Plasma / Q000378:metabolism*; D013931:Thromboxanes / Q000032:analysis / Q000378:metabolism
chemical_list: D015415:Biomarkers; D013931:Thromboxanes; D023201:CD40 Ligand