Benefit of Prestorage Leukocyte Depletion of Single–Donor Platelet Concentrates

Abstract

Background and Objectives: The presence of contaminating white blood cells (WBCs) in platelet concentrates is associated with transfusion reactions and may adversely alter the quality of platelets during storage. Leukocyte depletion by filtration of platelets has been increasingly used to avoid these complications. However, the best time for filtration and the benefits of filtering single–donor platelet concentrates (thrombapheresis, TH) have yet to be clearly defined. Methods: In a randomized study of 202 TH collected with an Autopheresis C system, we determined whether prestorage filtration (preSF) of WBCs from TH as compared with poststorage (bedside) filtration (postSF) resulted in a better product. Levels of cytokines and C3a accumulating in the medium during storage, platelet activation state, in vivo platelet recovery, and transfusion reactions were compared in pre– and poststorage products. Results: As compared to preSF, significantly more postSF TH had detectable levels of tumor necrosis factor–α (TNF–α; 47 vs. 15%; p<0.0001) and interleukin 6 (13 vs. 3%; p = 0.02), lower pH (p<0.0001) and decreased levels of C3a (910 vs. 2,000 pg/ml; p<0.0001). Furthermore, platelet activation was increased in postSF TH (p = 0.022). PostSF TH tended to plug the bedside filter (27% of postSF TH delivered) from day 3 onward. There was also a significant difference in platelet recovery, postSF TH showing a lower corrected count increment (CCI; p = 0.0055) when taking into account the postSF TH that plugged filters (CCI = 0), but no difference when plugged TH were excluded. A correlation could be established between TNF–α levels and poor in vivo recovery (p<0.0001). Febrile nonhemolytic transfusion reactions were low in both groups (4 and 9%). Conclusion: These results indicate a benefit of preSF TH as compared with postSF TH based on the following parameters: decrease in cytokine levels, less platelet activation, maintenance of higher pH, and more efficient use of stored platelets (27% of postSF TH were lost because of plugging of filters). These results apply particularly to the Autopheresis C systems with its high initial WBC content.