Measuring Plasma NETs and Cytokines in COVID-19

The presence of NETs in plasma was determined by measuring the concentration of double-stranded DNA (dsDNA) in a Quibit™ 3.0 Fluorometer (Thermo Fisher), and the levels of histone-complexed DNA (i.e., cell-free nucleosomes) using the Cell Death Detection ELISA^PLUS (Roche). The protein concentrations of IL-6, IL-8, IL-26, and TNFα in human plasma were quantified using ELISA (IL-6, IL-8, and TNFα: R&D Systems; IL-26: Cusabio) according to the manufacturer’s instructions. Cytokine concentrations were measured in samples from all patients and controls, but the plasma concentration of dsDNA and cell-free nucleosomes could only be measured in 32 out of 49 patients from the COVID-19 group, and 26 out of 27 participants from the Control group. Results on the specific levels of dsDNA, cell-free nucleosomes, IL-6, IL-8, and TNFα were already available from a previous publication on this patient material (8 (link)). However, all data on IL-26, as well as all comparisons presented in the current study have not been published elsewhere.