Low expression of PRDX2 protein in AML blasts is associated with a poor prognosis. (A) Intensity of PRDX1 staining in tissue arrays from AML BM biopsies. PRDX1 low staining (grade 1-3; left) and positive (grade 4-5; right). AML BM biopsies were analyzed by IHC. (B) Intensity of PRDX2 staining in tissue arrays from AML BM biopsies. PRDX2 low/negative (left) and high (right). AML BM biopsies were analyzed by IHC. Pictures were taken on an Axio Imager M1 (Carl Zeiss Imaging Systems) with a 63×/1.4 oil objective at room temperature and processed by AxioVision Release 4.5 (Carl Zeiss Imaging Systems). (C) Kaplan-Meier plots were generated to compare EFS among patients with AML with low or high expression of peroxiredoxins. Results are indicated for the entire patient cohort and for the more homogenous group with intermediate cytogenetics. Patients whose blasts expressed low levels of PRDX2 only experienced worse EFS compared with patients with AML with high expression of PRDX2 (P = .028, log-rank test). In patients with intermediate cytogenetics, low expression of PRDX2 was associated with poor EFS (P = .006). PRDX1 expression levels did not correlate with EFS. (D) Analyses of OS with regard to peroxiredoxin repression. The Kaplan-Meir plots indicate that patients with AML with low PRDX2 expression in leukemic blasts show decreased OS compared with patients with AML with high expressing blasts (P = .050). In patients with intermediate cytogenetics a close association between low expression of PRDX2 in leukemic blasts and poor OS was found (P = .031). PRDX1 expression did not correlate with OS.