TABLE 1

Suggested Whole-Blood Processing Practices

SerumPlasma and Buffy CoatDNARNA
Collection (from whole blood)Use the same collection tubes for each sample to reduce changes in analytes23,8588Use the same collection tubes for each sample to reduce changes in analytes23,8588Sodium citrate or EDTA tubes are optimal89PAXgene tubes
Heparin should be avoided89
Time to centrifugation30–60 min or longer if patient is treated with anticoagulants67Immediately25,63,64Immediately25,63,64For the PAXgene tubes, sample must be incubated at RTa for a minimum of 2 h to ensure complete lysis and inactivation of ribonucleases before isolation90
Samples processed in <30 min can retain cellular components that may influence downstream analysis67RNA in PAXgene tube is stable for 72 h at RT, 4–6 d at 4°C90
Keep lag time before centrifugation constant to reduce sample variability69,70Keep lag time before centrifugation constant to reduce sample variability69,70Keep lag time before centrifugation constant to reduce sample variability69,70
Time to freezeImmediately68,72Immediately68,72Process DNA before freezing to avoid hemolysis58RNA in PAXgene tube is stable for up to 5 d at RT and up to 12 mo at –20°C91
Storage−70°C minimum to maximize storage duration without changes in sample quality75,76−70°C minimum to maximize storage duration without changes in sample quality75,76Stable at 4°C for several weeks, at –20°C for months, and at –80°C for years71−70°C minimum once RNA has been isolated25
Freeze-thawFreeze-thaw should be limited to only 1 cycle to ensure sample integrity76Freeze-thaw should be limited to only 1 cycle to ensure sample integrity76Freeze-thaw should be limited to only 1 cycle to ensure sample integrity77Freeze-thaw should be limited to only 1 cycle to ensure sample integrity25
  • a RT = 20–25°C.