title: Clinical evaluation of the levels of 12 cytokines in serum/plasma under             various storage conditions using evidence biochip arrays.
abstract: Cytokines are a group of peptides which form a sophisticated network to             modulate multiple cellular events. Within such a network, and through complex             feedback mechanisms, cytokine functions are largely interdependent and closely             associated with a number of pathological processes. In the present study, the             EVIDENCE 180 system was used to study the effects of storage temperature and repeated             freeze/thaw cycles on the concentration of 12 cytokines in various sample types.             Samples were collected from 9 healthy volunteers and stored by 3 methods: gel,             glass and lithium heparin (LH) tubes. Immediately following collection, the concentration             of each cytokine in the samples was measured. Cytokine concentrations of the 3 sample             types that did not undergo repeated freeze/thaw cycles were compared with those             subjected to 1‑10 freeze/thaw cycles. In addition, the dynamic changes of 6 sample             types which were stored at 4˚C for 6 h to 6 days was analyzed. In addition, the             within‑ and between‑run precision of 12 cytokines on the biochip array was evaluated.             Interleukin (IL)‑8, vascular endothelial growth factor (VEGF) and epidermal growth             factor (EGF) concentrations were lower in plasma compared with serum. Cytokine             levels in serum and plasma were affected by several freeze/thaw cycles with IL‑1β,             ‑4 and ‑10 increasing significantly following 1 freeze/thaw cycle and remaining             at stable increased levels for the duration of the additional 9 cycles. In separated             serum samples in gel and glass tubes stored at 4˚C for 6 days, no difference in             concentration of the 12 cytokines was identified. In the other 4 sample types,             IL‑8, VEGF, tumor necrosis factor α and EGF levels were altered when stored at             4˚C. Results indicate that the EVIDENCE 180 system is stable and plasma was observed             as the best sample type to determine concentration of the 12 cytokines using this             biochip array. Repeated freeze/thaw cycles and storage at 4˚C was identified to             affect the concentration of the 12 cytokines. The current study demonstrates that             repeated freeze/thaw cycles of samples must be avoid. In addition, results indicate             that plasma or serum must be separated immediately following centrifugation and             sample concentration should be measured as soon as possible.
authors.affiliation: Department of Clinical Biochemistry, Chinese PLA General Hospital, Beijing 100853, PR China.
authors.forename: Guang-Hong
authors.initials: GH
authors.lastname: Guo
authors.forename: Jin
authors.initials: J
authors.lastname: Dong
authors.forename: Xin-Hong
authors.initials: XH
authors.lastname: Yuan
authors.forename: Zhen-Nan
authors.initials: ZN
authors.lastname: Dong
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Tian
mesh_terms: D000293:Adolescent; D000328:Adult; D016207:Cytokines / Q000097:blood*; D005260:Female; D005615:Freezing; D006801:Humans; D008297:Male; D008875:Middle Aged; D040081:Protein Array Analysis; D011933:Reagent Kits, Diagnostic; D013048:Specimen Handling; D013696:Temperature; D013997:Time Factors; D055815:Young Adult
chemical_list: D016207:Cytokines; D011933:Reagent Kits, Diagnostic