title: Analytical performance of a multiplexed, bead-based cytokine detection system in small volume samples.
abstract: BACKGROUND
  Multiplexed cytokine measurement offers many advantages over the conventional enzyme-linked immunosorbent assay (ELISA) format when applied in large-scale epidemiological studies or clinical trials. In the present study we set out to define the reliability and consistency of a suspension multiplexed protein array, the cytometric bead array (CBA), in large-scale, longitudinal studies.
  
  
  METHODS
  The cytokines interleukin (IL)-5, IL-10, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) were measured in pediatric samples from childhood asthma and allergy studies. Analytical performance of CBA was determined in sample supernatants and CBA was compared to conventional ELISA.
  
  
  RESULTS
  Within-run and total imprecision were between 5.2%-10.8% and 5.6%-13.2%, respectively, at three different concentrations for all cytokines. Slopes of dilution linearity were between 1.01 and 1.31 for the four cytokines. The recovery rate at two different concentrations of the cytokines was between 97% and 113%. Lower limits of detection and quantification as well as functional sensitivity were determined. Comparison of the multiplex array and solid phase method showed good correlation with r between 0.82 and 0.93. The sample volume required for the multiplex format was 25% of the ELISA sample volume.
  
  
  CONCLUSIONS
  CBA analytical evaluation and comparison to an ELISA format demonstrated high reproducibility, sensitivity and good applicability for small volume samples.
authors.affiliation: Institute of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, Philipps University, Marburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Bomert
authors.forename: Gabi
authors.initials: G
authors.lastname: Köllisch
authors.forename: Marjut
authors.initials: M
authors.lastname: Roponen
authors.forename: Roger
authors.initials: R
authors.lastname: Lauener
authors.forename: Harald
authors.initials: H
authors.lastname: Renz
authors.forename: Petra I
authors.initials: PI
authors.lastname: Pfefferle
authors.forename: Nadia
authors.initials: N
authors.lastname: Al-Fakhri
mesh_terms: D016207:Cytokines / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation / Q000379:methods; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D016207:Cytokines