A fully-automated, six-plex single molecule immunoassay for measuring cytokines in blood

We report a system and assay for performing fully-automated measurement of 6 proteins simultaneously with single molecule sensitivity. The system combines handling of samples, reagents, and consumables, with a module for imaging single molecule arrays (Simoa) to enable immunoassays that have high sensitivity (similar to fg/mL), are multiplexed, and are fully-automated. A 6-plex cytokine Simoa assay for IL-6, TNF-alpha, GM-CSF, IL-10, IL-1 beta, and IL-1 alpha was developed on the system. The assays had limits of detection in the range 0.01-0.03 pg/mL, and the average imprecision (CV) of the Simoa signal was 4.2%. This assay was used to measure the concentrations.of these cytokines in the plasma of patients with Crohn's Disease (CD), before and after treatment with anti-TNF-alpha antibody drugs, and in the serum of Type 1 diabetics. Concentrations of TNF-alpha and IL-6 in the CD samples determined using the fully-automated, multiplex Simoa assay had good correlation with the manual, single-plex assays previously reported. Drug treatment caused reductions in the mean concentration of all 6 cytokines in the plasma of CD patients. The concentrations of 4 cytokines were significantly higher in diabetics compared to healthy controls. The system could enable the widespread, multiplexed measurement of protein biomarkers with low abundance. (C) 2015 Elsevier B.V. All rights reserved.