title: Plasma levels of sphingosine 1-phosphate are strongly correlated with haematocrit, but variably restored by red blood cell transfusions.
abstract: Anaemia and RBC (red blood cell) transfusion may be associated with worse clinical outcomes, especially with longer blood storage duration prior to transfusion. The mechanisms underlying these harmful effects are unknown. RBCs have been proposed to buffer plasma S1P (sphingosine 1-phosphate), a lysophospholipid essential for the maintenance of endothelial integrity and important in the regulation of haematopoietic cell trafficking. The present study examined the effect of anaemia, RBC transfusion and RBC storage duration on plasma S1P levels. Plasma S1P from 30 individuals demonstrated a linear correlation with Hct (haematocrit; R2 = 0.51, P < 0.001) with no evidence for a plateau at Hct values as low as 19%. RBC transfusion in 23 anaemic patients with baseline mean Hct of 22.2 ± 0.34% (value is the mean ± S.D.) increased Hct to 28.3 ± 0.6% at 72 h. Despite an Hct increase, RBC transfusion failed to elevate plasma S1P consistently. A trend towards an inverse correlation was observed between RBC storage duration and the post-transfusion increase in plasma S1P. After 30 days of storage, RBC S1P decreased to 19% of that observed in fresh (3-7-day-old) RBC segments. RBC membranes contain low levels of both S1P phosphatase and S1P lyase activities that may account for the decline in S1P levels with storage. Our results support a role for RBCs in buffering plasma S1P and identify a disturbance in the capacity after transfusion. Changes in S1P content may contribute to an RBC storage lesion. Further studies should investigate the clinical significance of alterations in circulating S1P levels and the potential value of enriching stored RBCs with S1P.
authors.affiliation: Division of Cardiovascular Medicine, The Gill Heart Institute, 741 S. Limestone Street, Lexington, KY 40536-0509, USA.
authors.forename: Samy
authors.initials: S
authors.lastname: Selim
authors.forename: Manjula
authors.initials: M
authors.lastname: Sunkara
authors.forename: Abdelghaffar K
authors.initials: AK
authors.lastname: Salous
authors.forename: Steve W
authors.initials: SW
authors.lastname: Leung
authors.forename: Evgeny V
authors.initials: EV
authors.lastname: Berdyshev
authors.forename: Alison
authors.initials: A
authors.lastname: Bailey
authors.forename: Charles L
authors.initials: CL
authors.lastname: Campbell
authors.forename: Richard
authors.initials: R
authors.lastname: Charnigo
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Morris
authors.forename: Susan S
authors.initials: SS
authors.lastname: Smyth
mesh_terms: D000328:Adult; D000368:Aged; D000740:Anemia / Q000097:blood* / Q000628:therapy; D001793:Blood Preservation; D017707:Erythrocyte Transfusion; D004912:Erythrocytes / Q000502:physiology; D005260:Female; D006400:Hematocrit; D006801:Humans; D008075:Lipoproteins, HDL / Q000097:blood; D008190:Lyases / Q000097:blood; D008246:Lysophospholipids / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010744:Phosphoric Monoester Hydrolases / Q000097:blood; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000097:blood; D013997:Time Factors
chemical_list: D008075:Lipoproteins, HDL; D008246:Lysophospholipids; C060506:sphingosine 1-phosphate; D010744:Phosphoric Monoester Hydrolases; D008190:Lyases; D013110:Sphingosine