title: Variability of serum levels of tumor necrosis factor-alpha, interleukin 6, and soluble interleukin 6 receptor over 2 years in young women.
abstract: Serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), and soluble interleukin 6 receptor (sIL-6R) have been studied as risk factors of cardiovascular disease in longitudinal studies. However, it is unknown about their long-term intra-individual variations and whether single measurements of these cytokines and receptor are reliable biomarkers in epidemiological studies. In this study, serum levels of TNF-alpha, IL-6, and sIL-6R were assayed by ELISAs in 36 young, healthy women from whom three blood samples were collected at 12-month intervals over 2 years, and the intraclass correlation coefficients (ICC) were estimated. The ICC of 0.73 (95% CI=0.49-0.79) for TNF-alpha was comparable to those of other commonly used biomarkers, justifying its use in epidemiological studies. The ICC of 0.48 (95% CI=0.25-0.58) for IL-6 was not optimal. However, IL-6 has been demonstrated as a consistent risk factor for cardiovascular disease, suggesting it could still be a useful biomarker if its disease association is substantial. The ICC of 0.36 (95% CI=0.10-0.47) for sIL-6R was relatively low, and multiple samples would need to be collected in prospective studies for this receptor.
authors.affiliation: Department of Epidemiology & Population Health, Albert Einstein College of Medicine, Bronx, NY 10461, USA. ho@aecom.yu.edu
authors.forename: Gloria Y F
authors.initials: GY
authors.lastname: Ho
authors.forename: Xiao-Nan
authors.initials: XN
authors.lastname: Xue
authors.forename: Robert D
authors.initials: RD
authors.lastname: Burk
authors.forename: Robert C
authors.initials: RC
authors.lastname: Kaplan
authors.forename: Elaine
authors.initials: E
authors.lastname: Cornell
authors.forename: Mary
authors.initials: M
authors.lastname: Cushman
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D015415:Biomarkers / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007249:Inflammation; D015850:Interleukin-6 / Q000097:blood*; D030361:Papillomavirus Infections / Q000097:blood; D011446:Prospective Studies; D019947:Receptors, Interleukin-6 / Q000097:blood*; D012016:Reference Values; D015203:Reproducibility of Results; D012307:Risk Factors; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
chemical_list: D015415:Biomarkers; D015850:Interleukin-6; D019947:Receptors, Interleukin-6; D014409:Tumor Necrosis Factor-alpha