Regulation of the lysophosphatidylserine and sphingosine 1-phosphate levels in autologous whole blood by the pre-storage leukocyte reduction

Background and objectives: The effect of leukoreduction and storage periods on the accumulation of bioactive lysophospholipids and substances in human autologous blood (AB units) has not been fully investigated. Materials and methods: The accumulation of bioactive lysophospholipids such as sphingosine 1-phosphate (S1P) and lysophosphatidylserine (LysoPS) in AB units during the storage was investigated. The time-dependent changes and the effect of the filtration in pre-storage leuckoreduction (LR) and unmodified samples derived from 46 AB units were analysed. Additionally, the changes of lysophospholipids and platelet releasate, namely β-thromboglobulin (β-TG), induced by exposure of whole blood (WB) or platelet-rich plasma (PRP) to the filter material were analysed. Results: LysoPS, but not S1P levels, time-dependently and significantly increased in both unmodified and LR samples. LysoPS significantly decreased in LR compared with unmodified samples, whereas S1P increased in LR compared with unmodified samples. In addition, exposure of WB and/or PRP to the filter material in vitro resulted in increased levels of S1P, LysoPS and β-TG. Conclusions: LR effectively reduced the accumulation of LysoPS in AB units. On the other hand, it increased concentrations of S1P due to platelet activation by exposure to the filter material. These suggest that increases of S1P levels in LR and LysoPS in the unmodified samples were mainly caused by the leukocytes and/or platelets and that LR was effective in inhibiting the accumulation of LysoPS.