Oxidative DNA damage in reconstituting CD3⁺T cells after allo-SCT. (A) Serum concentration of 8-OHdG of HDs (n = 18), of patients who underwent auto-SCT (n = 16), and of patients between day 30 to 120 after allo-SCT (n = 50) was quantified using ELISA. 8-OHdG serum levels of HDs were compared with that of patients who underwent allo-SCT at each individual time point, using an unpaired t test. (B) 8-OHdG levels were analyzed in CD3⁺ T cells of HDs (n = 52), patients who underwent auto-SCT (n = 16), and patients who underwent allo-SCT (n = 66) using FACS, based on the MFI. Representative histograms are shown in the right panel. The T cells’ 8-OHdG MFI in HDs was compared with that of patients who underwent allo-SCT at each individual time point using an unpaired t test. (C) The 8-OHdG and ph2ax MFIs of allo-SCT CD3⁺ T cells at all tested time points were correlated using the Pearson correlation (r = Pearson correlation coefficient). (D) Based on the mean 8-OHdG MFI in T cells from time points after allo-SCT, patients (n = 66) were grouped into a high (8-OHdG^hi, n = 22), intermediate (8-OHdG^int, n = 22), and low (8-OHdG^lo, n = 22) cohort. (E) The post–allo-SCT course of the 8-OHdG MFI in CD3⁺ T cells is shown. The horizontal dotted line represents the mean value of HD (n = 54). (F) The post–allo-SCT course of the serum 8-OHdG concentrations is shown. The horizontal dotted line represents the mean value of HD (n = 8). (G) The relative proportion of CD4⁺ and CD8⁺ T-cell subsets (ie, central memory/CM, EMRA, EM, and naïve) is shown for the post–allo-SCT period. (H) Frequency of naturally occurring CD3⁺CD4⁺CD25⁺CD127^lo/neg T_regs was assessed using FACS and compared between the 3 cohorts after allo-SCT. P value: ∗P < .05; ∗∗P < .01; ∗∗∗P < .001. “n” indicates the sample number; bars represent the standard error of the mean. ELISA, enzyme-linked immunosorbent assay.