Bio one vacuette

Blood samples were collected from all patients upon admission, and multiple blood samples were dynamically collected in about half of these patients (96/196, 49.0%). Specifically, the samples were collected twice in 51 patients (on admission; 3–4 days after admission) and thrice in 45 patients (on admission; 3–4 days after admission; 7–8 days after admission). Blood samples were collected by venepuncture into vacuum tubes (Greiner Bio-One Vacuette®) containing separation gel, then were centrifuged at 4000rpm×10 min at 4°C (Kubota S700 T Centrifuge, Fujioka, Japan) within 2 h, then stored at 4°C. Considering the possibility of degradation of cytokine concentrations resulted from varied storage duration, the upper layer of serum was extracted and transferred into sterile cryogenic tubes using micropipettes within 3 days of storage, which was prior to freezing at −80°C immediately for further use without freeze/thaw cycles.