title: Multiplex assay reliability and long-term intra-individual variation of serologic inflammatory biomarkers.
abstract: Circulating cytokines, chemokines, and soluble cytokine receptors can serve as biomarkers of inflammation and immune dysregulation. Good reliability of multiplex platforms, which allow for simultaneous, comprehensive biomarker assessment, is critical for their utility in epidemiologic studies. We examined the reliability of the Meso-Scale Discovery (MSD) platform to simultaneously quantitate 15 cytokines and chemokines and the Luminex platform (R&D Systems) to quantitate 5 soluble receptors and 2 chemokines and cytokines and evaluated long-term within-person correlation of these biomarkers.
  
  
  
  The detectability and reliability of these assay systems were assessed using the same external controls across plates and archived sera from 250 HIV-men in the Multicenter AIDS Cohort Study. Using up to four visits per person from 1984 to 2009, age-adjusted intraclass correlation coefficients (ICC) of biomarkers with >80% detectability (CCL11, CXCL8, CXCL10, CCL2, CCL4, CCL13, CCL17, CXCL13, IL-10, IL-12p70, IL-6, TNF-α, BAFF, sCD14, sCD27, sgp130, sIL-2Rα, and sTNF-R2) were obtained using linear mixed models.
  
  
  
  Most biomarkers were detectable in 80% of control samples; IFN-γ, GM-CSF, and IL-2 were undetectable in >20% of samples. Among the HIV-uninfected men, most biomarkers showed fair to strong within-person correlation (ICC>0.40) up to 15years. The ICC for CXCL8 was good in the short term but decreased with increasing time between visits, becoming lower (ICC<0.40) after 8years.
  
  
  
  These multiplexed assays showed acceptable reliability for use in epidemiologic research, despite some technical variability and limitations in cytokine quantitation. Most biomarkers displayed moderate-to-excellent intra-individual variability over the long term, suggesting their utility in prospective studies investigating etiologic associations with diverse chronic conditions.
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. Electronic address: hmckay4@jhu.edu.
authors.forename: Heather S
authors.initials: HS
authors.lastname: McKay
authors.affiliation: Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Margolick
authors.affiliation: Departments of Obstetrics & Gynecology, UCLA, Los Angeles, CA, USA; Department of Microbiology, Immunology & Molecular Genetics, UCLA, Los Angeles, CA, USA; David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Epidemiology, UCLA Fielding School of Public Health, University of California, Los Angeles, CA, USA.
authors.forename: Otoniel
authors.initials: O
authors.lastname: Martínez-Maza
authors.affiliation: Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Lopez
authors.affiliation: Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: John
authors.initials: J
authors.lastname: Phair
authors.affiliation: University of Pittsburgh, School of Public Health, Pittsburgh, PA, USA.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Rappocciolo
authors.affiliation: Duke Human Vaccine Institute, Department of Medicine, Duke University School of Medicine, Duke University, Durham, NC, USA.
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Denny
authors.affiliation: Departments of Obstetrics & Gynecology, UCLA, Los Angeles, CA, USA.
authors.forename: Larry I
authors.initials: LI
authors.lastname: Magpantay
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Lisa P
authors.initials: LP
authors.lastname: Jacobson
authors.affiliation: Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Jay H
authors.initials: JH
authors.lastname: Bream
mesh_terms: D015415:Biomarkers / Q000097:blood; D016207:Cytokines / Q000097:blood*; D005260:Female; D015658:HIV Infections / Q000097:blood*; D015497:HIV-1; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood*; D008297:Male; D060885:Multiplex Polymerase Chain Reaction; D011446:Prospective Studies
chemical_list: D015415:Biomarkers; D016207:Cytokines; D018836:Inflammation Mediators
keywords: Inflammatory biomarkers; Intraclass correlation; Multiplex assay reliability; Reliability