Benefit of prestorage leukocyte depletion of single-donor platelet concentrates

Background and Objectives: The presence of contaminating white blood cells (WBCs) in platelet concentrates is associated with transfusion reactions an d may adversely alter the quality of platelets during storage. Leukocyte de pletion by filtration of platelets has been increasingly used to avoid thes e 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 accumulat ing in the medium during storage, platelet activation state, in vivo platel et recovery, and transfusion reactions were compared in pre- and poststorag e products. Results: As compared to preSF, significantly more postSF TH had detectable levels of tumor necrosis factor-alpha (TNF-alpha; 47 vs. 15%; p <0.0001) and interleukin 6 (13 vs. 3%; p = 0.02), lower pH (p<0.0001) and d ecreased levels of C3a (910 vs. 2,000 pg/ml; p<0.0001). Furthermore, platel et activation was increased in postSF TH (p = 0.022). PostSF TH tended to p lug the bedside filter (27% of postSF TH delivered) from day 3 onward. Ther e was also a significant difference in platelet recovery, postSF TH showing a lower corrected count increment (CCI; p = 0.0055) when taking into accou nt the postSF TH that plugged filters (CCI = 0), but no difference when plu gged TH were excluded. A correlation could be established between TNF-a lev els and poor in vivo recovery (p < 0.0001). Febrile non hemolytic transfusi on 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 foll owing parameters: decrease in cytokine levels, less platelet activation, ma intenance of higher pH, and more efficient use of stored platelets (27% of postSF TH were lost because of plugging of filters). These results apply pa rticularly to the Autopheresis C systems with its high initial WBC content.