Annals of Clinical Biochemistry > Volume 45, Number 4 > Pp. 356-363

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Original Articles

Plasma sphingosine-1-phosphate measurement in healthy subjects: close correlation with red blood cell parameters

Ryunosuke Ohkawa¹, Kazuhiro Nakamura¹, Shigeo Okubo¹, Shigemi Hosogaya², Yukio Ozaki², Minoru Tozuka¹, Noriko Osima³, Hiromitsu Yokota¹, Hitoshi Ikeda^1,4 and Yutaka Yatomi^1,4

¹ Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan; ² Department of Clinical and Laboratory Medicine, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan; ³ Department of Biomolecular Science, Faculty of Science, Toho University, Chiba, Japan; ⁴ Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan

Corresponding author: Dr Yutaka Yatomi. Email: yatoyuta-tky{at}umin.ac.jp

Background: Since sphingosine-1-phosphate (Sph-1-P) plays an important role as an extracellular mediator through interaction with specific cell surface receptors, especially in the area of vascular biology and immunology/haematology, determination of its plasma concentration may become important from the clinical viewpoint. Thus, we attempted to develop a method of measuring the plasma Sph-1-P concentration for use in the clinical laboratory setting.

Methods: After two-step lipid extraction, Sph-1-P was coupled with o-phthaldialdehyde, and the resultant fluorescent derivative was separated by high-performance liquid chromatography. C₁₇-Sph-1-P was used as the internal standard, instead of dihydrosphingosine-1-phosphate, which had been used previously for the same purpose but was actually detected in plasma.

Results: Our procedures for preparing the plasma samples and assay Sph-1-P were found to be satisfactory for clinical laboratory testing. The plasma Sph-1-P concentrations were significantly higher in men (413.1 ± 52.0 nmol/L; mean ± SD) than in women (352.4 ± 39.7 nmol/L). Unexpectedly, strong positive correlations were found between the plasma Sph-1-P concentration and red blood cell (RBC)-related parameters, rather than platelet-related parameters.

Conclusions: Our present study confirmed the possibility of the clinical introduction of plasma Sph-1-P measurement, and in addition, suggested that RBCs may be involved in the regulation of plasma Sph-1-P concentrations.

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