Human blood sample preparation
Venous blood was collected from healthy volunteers using EDTA
vacutainers (Becton Dickinson, Franklin Lakes, NJ) following informed
consent. The study was approved by the University of Louisville
Institutional Review Board (08.018). Volunteers were excluded for the
presence of chronic illness, use of anti-inflammatory or
immunosuppressive medications or signs of acute illness. Whole blood was
aliquoted in 1 mL volumes in Falcon polypropylene culture tubes (Fisher
Scientific, Waltham, MA). Samples were incubated for up to 18 hours in
various conditions at 37°C with 5% carbon dioxide and gentle vortexing
every 4 hours. After 18 h, whole blood was centrifuged at 3000 RPM for 3
minutes to obtain plasma which was stored at -80°C until later analysis.
Prior work determined optimal sample timing [35].