Stability of soluble adhesion molecules, selectins, and C-reactive protein at various temperatures: implications for epidemiological and large-scale clinical studies.
BACKGROUND
We assessed the impact of sample storage conditions on soluble vascular cell adhesion molecules (sVCAM), soluble intracellular adhesion molecules (sICAM-1), soluble (s)E-selectin, C-reactive protein (CRP), and sP-selectin.


METHODS
Markers were measured by ELISA in venous blood from 10 healthy volunteers on aliquots stored as plasma or whole blood at 4, 21, or 30 degrees C for 1-5 days and after 1-5 freeze-thaw cycles. We compared results on these samples to results for samples processed immediately and stored at -80 degrees C. Statistical models assessed time-related effects and effects of postprocessing conditions.


RESULTS
Using an upper limit of 10% variation from baseline with P >0.05, we found that stability duration in plasma was 5 days for sVCAM-1 and sICAM-1 and at least 2 days for sE-selectin at 4, 21, and 30 degrees C and 5 days for CRP at 4 and 21 degrees C and 1 day at 30 degrees C. Stability duration in whole blood was 5 days for sVCAM-1 and sICAM-1 and at least 2 days for sE-selectin at 4, 21, and 30 degrees C and 5 days for CRP at 4 and 21 degrees C and 2 days at 30 degrees C. sP-selectin was not stable in plasma or whole blood. sICAM-1, sVCAM-1, CRP, and sE-selectin were stable after 5 freeze-thaw cycles.


CONCLUSIONS
sVCAM-1, sICAM-1, and CRP are stable in plasma or whole blood at 4 and 21 degrees C for at least 3 days and sE-selectin for 2 days. sP-selectin is not stable and therefore requires immediate assay.
Diabetes Trials Unit, Oxford Centre for Diabetes, Endocrinology and Medicine, University of Oxford, United Kingdom. janine.hartweg@ndm.ox.ac.uk
Janine
J
Hartweg
Michael
M
Gunter
Rafael
R
Perera
Andrew
A
Farmer
Carole
C
Cull
Casper
C
Schalkwijk
Astrid
A
Kok
Harry
H
Twaalfhoven
Rury
R
Holman
Andrew
A
Neil
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D001800:Blood Specimen Collection; D002097:C-Reactive Protein / Q000032:analysis*; D015925:Cryopreservation; D019040:E-Selectin / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019007:P-Selectin / Q000097:blood*; D012995:Solubility; D013696:Temperature; D013997:Time Factors; D019010:Vascular Cell Adhesion Molecule-1 / Q000097:blood*
D015415:Biomarkers; D019040:E-Selectin; D019007:P-Selectin; D019010:Vascular Cell Adhesion Molecule-1; D002097:C-Reactive Protein