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Effects of sample handling on the stability of interleukin 6, tumour necrosis factor-alpha and leptin

Flower, L; Ahuja, RH; Humphries, SE; Mohamed-Ali, V; (2000) Effects of sample handling on the stability of interleukin 6, tumour necrosis factor-alpha and leptin. CYTOKINE , 12 (11) 1712 - 1716. 10.1006/cyto.2000.0764.

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Abstract

Detected levels of IL-6, TNF-alpha and leptin may be affected by methods of storage, anticoagulant or repeated freezing-thawing. Blood samples from 22 healthy subjects were: (i) allowed to stand for 1, 2, 4 or 6 h prior to, or after separation, before freezing at -70 degreesC; (ii) taken into tubes with lithium heparin, sodium citrate, EDTA or no anticoagulant, separated and frozen; and (iii) separated, and plasma repeatedly freeze-thawed for up to six cycles prior to assay. Leptin was assayed by RIA, and IL-6 and TNF-alpha by high-sensitivity ELISA, (i) IL-6 and TNF-alpha levels were not altered significantly in separated samples but IL-6 declined by mean (SEM) 14.3% (3.7%) and TNF-alpha increased by 9.6% (2.3%) in samples left unseparated for 4 h (P=0.003 and 0.002, respectively). Leptin remained unchanged. (ii) Serum and EDTA-plasma samples gave comparable results for all three cytokines, but levels in the other anticoagulant samples were highly variable. (iii) IL-6 and leptin levels were not altered by up to 6 cycles of freeze-thawing, but TNF-alpha increased by 17.0% (3.7%) after 3 cycles, Concentrations of these molecules are significantly altered by storage conditions, therefore they need to be standardized for epidemiological and clinical studies, and between-study comparisons of levels may not be reliable. (C) 2000 Academic Press.

Type:Article
Title:Effects of sample handling on the stability of interleukin 6, tumour necrosis factor-alpha and leptin
DOI:10.1006/cyto.2000.0764
Keywords:IL-6, TNF-alpha, leptin, stability, storage, ADIPOSE-TISSUE
UCL classification:UCL > School of Life and Medical Sciences > Faculty of Medical Sciences > Medicine (Division of)
UCL > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Cardiovascular Science

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