The Effect of Pre-analytical Handling on the Stability of Fractalkine, Monocyte Chemoattractant Protein 1 (MCP-1), Interleukin 6 and Interleukin 8 in Samples of Human Cerebrospinal Fluid: A Prospective Cohort Study.

Abstract BackgroundCytokine networks in cerebrospinal fluid (CSF) are important to our understanding of several neuroinflammatory diseases. Knowledge about optimal handling of samples is limited but important to minimize bias and reduce costs in CSF biomarker studies. The aim of this study was to examine the effect of storage temperature and time delay from CSF sample collection until freezing on the concentration levels of 11 different cytokines thought to be associated with chronic pain.MethodsCSF samples from 21 individuals undergoing hip or knee arthroplasty under spinal anesthesia were divided between two tubes. One tube was stored and centrifuged (within 30 minutes) at room temperature, and one tube was stored in ice water and centrifuged (within 30 minutes) at 4˚C. Each tube was split into six vials that were frozen at -80 ˚C, 0.5, 1, 2, 3, 4, or 5 hours after collection. Cytokines were analyzed using a multiplex panel. A random effect panel data regression was conducted for each biomarker including the variables of storage temperature until freezing and time delay. ResultsFour cytokines had detectable levels: Fractalkine, monocyte chemoattractant protein 1(MCP-1), interleukine 6 (IL-6), and interleukine 8 (IL-8). There was no significant effect of storage temperature and time delay on MCP-1, IL-6, or IL-8 levels. Fractalkine levels showed no clear trend. No concentration differences were observed between samples kept in ice water and those at room temperature except at the 3-hour time point, and there was no overall significant effect of time delay on fractalkine concentration.ConclusionsWe found no clear effect of storage temperature and time delay up to five hours from sample collection until freezing on the CSF concentrations of fractalkine, MCP-1, IL-6, or IL-8.Trial registrationNot applicable as the study was not an intervention study.