Flow cytometric assessment of agonist-induced P-selectin expression as a measure of platelet quality in stored platelet concentrates.

Background Platelet (PLT) function in PLT concentrates declines during storage and is further affected by pathogen reduction treatment. Flow cytometric assessment of agonist-induced P-selectin expression can be used to assess PLT function in patients with thrombocytopenia. The aim of this study was to evaluate how this functional test relates to established in vitro measures of PLT function. Study Design and Methods Six units of PLTs in plasma and 6 units of riboflavin and ultraviolet ( Mirasol, Terumo BCT)-treated PLTs in plasma were sampled on Days 2, 6, 8, and 10 after donation. PLT concentration, Annexin 5 A staining, ThromboLUX (LightIntegra) thrombelastography, and P-selectin expression, both in unstimulated PLTs and in response to concentration series of adenosine diphosphate, collagen-related peptide, and thrombin receptor-activating peptide (TRAP), were measured. Results For PLTs in plasma Annexin 5 A expression increased by 0.60% (95% confidence interval [ CI], 0.40%-0.80%) and P-selectin expression increased by 1.2% (95% CI, 0.80%-1.6%) per day. Responsiveness to TRAP simultaneously decreased by 1.3% (95% CI, 0.80%-1.8%) per day. After Mirasol treatment ThromboLUX scores decreased 3.3 points (95% CI, 0.2-6.4 points) from 22 to 19 points, Annexin 5 A expression increased by 4.8% (95% CI, 3.3%-6.2%), and P-selectin expression increased by 13% (95% CI, 10%-16%), all averaged over the entire storage period. Responsiveness to TRAP simultaneously decreased by 19% (95% CI, 17%-21%). Conclusions Our results suggest flow cytometric measurement of agonist-induced P-selectin expression can measure PLT quality decline over the entire range encountered during 10-day storage of both standard PLTs and Mirasol-treated PLTs in plasma. [ABSTRACT FROM AUTHOR]