Effects of storage time and exogenous protease inhibitors on plasma protein levels.

Author(s): Ayache S, Panelli M, Marincola FM, Stroncek DF

Publication: Am J Clin Pathol, 2006, Vol. 126, Page 174-84

PubMed ID: 16891190 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to determine the effects of protease inhibitors, centrifugation at 1600 x g for 15 min rather than 2500 x g for 8 min, and delayed separation of plasma on the levels of 97 chemokines and cytokines.

   Summary of Findings:

   Storage of whole blood for 2 hours at room temperature prior to separation of plasma resulted in significant increases in the levels of 37 of 97 proteins in EDTA plasma and 31 of 97 proteins in EDTA plus protease inhibitor plasma when compared to plasma specimens that were prepared immediately (p< 0.01). These included 15 interleukins, 4 metalloproteases, and 10 growth factors. In addition, the level of NT-proBNP decreased significantly in plasma with protease inhibitors after 2 hours of storage. The average magnitude of the changes in protein levels ranged between 1.18-fold and 17.5-fold. The use of protease inhibitors resulted in significant changes in plasminogen activator inhibitor-1 (PAI-1), Eotaxin 2, Exodus II, and NT-proBNP when plasma was prepared immediately and PAI-1, matrix metalloprotease-2, tissue inhibitor of metalloprotease-2, and intracellular adhesion molecule-1 when whole blood was left at room temperature for 2 hours. This led the authors to conclude that the use of protease inhibitors, with or without a modified inner capsule in the collection tube, did not result in overall significant changes in protein profiles. Furthermore, the use of different centrifugation speeds and durations for separation of plasma did not significantly alter protein profiles.

   Biospecimens

   • Bodily Fluid - Plasma
   • Bodily Fluid - Blood

   Preservative Types

   • Frozen

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Protein	ELISA

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Time at room temperature	0 h 2 h
   Storage	Storage temperature	-80 degrees C
   Analyte Extraction and Purification	Protease inhibitor	No protease inhibitor added Added prior to analysis
   Biospecimen Acquisition	Type of collection container/solution	Standard EDTA tubes EDTA plus protease inhibitors EDTA plus protease inhibitors with modified inner capsule
   Biospecimen Aliquots and Components	Centrifugation	Multiple durations compared Multiple speeds compared Centrifugation delays investigated

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