Increased markers for oxidative stress in untreated CLL patients. (A) Serum levels of 8-OdHG and MDA were quantified in HDs (n = 11-15) and CLL patients (n = 63) by ELISA. CLL samples were scored according to the percentile rank of the measured 8-OdHG and MDA concentrations (25th percentile: 1 point, 50th percentile: 2 points, 75th percentile: 3 points), respectively. Based on the cumulative score, patients were grouped into a cohort with intermediate/low (<4, ROS^int/low) and high ROS (>5, ROS^high) levels. The absolute number of (B) CD14⁺ monocytes, of (C) granulocytes, and of (D) CD5⁺CD19⁺CD23⁺ CLL cells per μL peripheral blood of ROS^int/low and ROS^high patients as measured by FACS. (E) A representative histogram of a FACS-analysis showing healthy B-cells (filled black) and CLL cells (black line) stained with a ROS-sensitive dye (CellROX) and an unstained control (filled gray). An overview of the CellROX-mean fluorescence intensity (MFI) in freshly isolated regular B-cells (n = 8) and CLL cells (n = 10) depicted as a scatter plot. (F) The proportion of patients with and without lymphocyte doubling among the ROS^int/low and ROS^high groups is shown. The statistical analysis was performed using a χ²-test. Bars indicate the standard error mean. Abbreviations: P, P-value; *P < .05; **P < .005; ***P < .001.