2.5. Cell-Free DNA (cfDNA) Levels in Peripheral Blood

The content of cell-free DNA (cfDNA) in the blood plasma was determined by ELISA using the Cell Death Detection ELISA kit (Roche, Sigma-Aldrich). The definition is based on quantitative sandwich ELISA. Two mouse antibodies produced against DNA (single and double stranded) and histones (H1, H2A, H2B, H3, and H4), specifically binding mono- and oligonucleosomes derived from the nuclei of eukaryotic cells (cat. no. 11 774 425 001, https://sigma-aldrich.com). Absorption with a wavelength of 450 ± 10 nm was measured on a Microplate ChroMate Reader tablet (Awareness Technology Inc., USA). We measured the concentration of the DNA of the ELISA kit-positive control by spectrophotometer (NanoPhotometer N-50, Implen, Germany). By diluting this positive control, calibration curves were constructed to quantify the DNA in our samples.