Die thrombozytäre Toll-like-Rezeptor 2-vermittelte Immunfunktion bleibt unter kurzzeitiger Kühl-Lagerung von Thrombozyten erhalten
Julia Zeller-Hahn (Würzburg / DE), Angela Kößler (Würzburg / DE), Katja Weber (Würzburg / DE), Sabine Kuhn (Würzburg / DE), Anna Kobsar (Würzburg / DE), Jürgen Kößler (Würzburg / DE)
Recently, it was demonstrated that short-term refrigeration of platelets for 1 h or 2 h - either in platelet-rich-plasma (PRP) or in stored platelet concentrates (PC) - is sufficient to generate platelets with higher hemostatic responsiveness. However, refrigeration may have impact on non-hemostatic functions of platelets. Therefore, the intention of this study was to investigate the effect of short-term refrigeration on specific toll-like receptor 2-mediated platelet functions, as previously explored.
PRP, freshly prepared from healthy donors, was stored at cold temperature (CT, 2-6 °C) for 1 or 2 h, or alternatively, at room temperature (RT, 20-24 °C), followed by analysis of TLR2-dependent platelet integrity. TLR2 expression, intracellular reactive oxygen species (ROS) production in H2DCFDA-loaded platelets and uptake of fluorescence-labeled synthetic TLR2 ligand Pam3CSK4, and fluorophore-conjugated fibrinogen were evaluated by flow cytometry. TLR2-induced release of chemokines PF4 (platelet factor 4), NAP-2 (neutrophil-activating peptide-2), sCD40L (soluble CD40 ligand), RANTES (Regulated on activation, normal T cell expressed and secreted) and PDGF (platelet-derived growth factor) was measured by immunoassays.
Compared to RT, TLR2 expression shows a slightly increasing tendency under storage at CT. The uptake of fibrinogen and the uptake of ligand Pam3CSK4 in unstimulated and Pam3CSK4-stimulated platelets is comparable at RT and CT. The basal and Pam3CSK4-induced production of intracellular ROS remains unchanged at both temperatures. Accordingly, the release of chemokines PF4, NAP-2, sCD40L, RANTES and PDGF is not relevantly affected by storage at CT.
Short-term refrigeration is an opportunity to generate platelets with higher hemostatic reactivity without tampering the function of platelet TLR2. Consecutively, the findings should be confirmed in platelets from PC, stored for different time periods. In general, further studies are required addressing immune-related mechanisms in stored platelets, including TLR-dependent functions and the influence of storage temperature.
The authors have no conflicts of interest to declare.