Temporal reliability of cytokines and growth factors in EDTA plasma
1 Department of Environmental Medicine, New York University Langone Medical Center, New York, NY, USA
2 New York University Cancer Institute, New York University Langone Medical Center, New York, USA
3 Department of Obstetrics and Gynecology, New York University Langone Medical Center, New York, NY, USA
4 Department of Medicine, University of Pittsburgh Cancer Institute, Division of Cancer Prevention and Population Science, University of Pittsburgh, Pittsburgh, USA
5 Department of Pathology, University of Pittsburgh, Pittsburgh, USA
6 Department of Ob/Gyn Reproductive Sciences, University of Pittsburgh, Pittsburgh, USA
7 Department of Clinical Sciences, Obstetrics and Gynecology, Umeå University, Umeå, Sweden
8 Department of Public Health and Clinical Medicine/Nutritional Research, Umeå University, Umeå, Sweden
9 Department of Medical Biosciences, Pathology, Umeå University, Umeå, Sweden
BMC Research Notes 2010, 3:302 doi:10.1186/1756-0500-3-302Published: 13 November 2010
Cytokines are involved in the development of chronic diseases, including cancer. It is important to evaluate the temporal reproducibility of cytokines in plasma prior to conducting epidemiologic studies utilizing these markers.
We assessed the temporal reliability of CRP, 22 cytokines and their soluble receptors (IL-1α, IL-1β, IL-1RA, IL-2, sIL-2R, IL-4, IL-5, IL-6, sIL-6R, IL-7, IL-8, IL-10, IL-12p40, IL-12p70, IL-13, IL-15, IL-17, TNFα, sTNF-R1, sTNF-R2, IFNα, IFNγ) and eight growth factors (GM-CSF, EGF, bFGF, G-CSF, HGF, VEGF, EGFR, ErbB2) in repeated EDTA plasma samples collected an average of two years apart from 18 healthy women (age range: 42-62) enrolled in a prospective cohort study. We also estimated the correlation between serum and plasma biomarker levels using 18 paired clinical samples from postmenopausal women (age range: 75-86).
Twenty-six assays were able to detect their analytes in at least 70% of samples. Of those 26 assays, we observed moderate to high intra-class correlation coefficients (ICCs)(ranging from 0.53-0.89) for 22 assays, and low ICCs (0-0.47) for four assays. Serum and plasma levels were highly correlated (r > 0.6) for most markers, except for seven assays (r < 0.5).
For 22 of the 31 biomarkers, a single plasma measurement is a reliable estimate of a woman's average level over a two-year period.