AML progression results in increased Tregs present at the primary sites of AML metastases. B6 mice were injected intravenously with 10⁶ C1498FFDsR cells and killed 6, 14, or 25 days after tumor injection. Flow cytometric analysis was performed on liver leukocytes and splenocytes. (A) Increased percentage of DsR⁺ tumor cells was found in the livers and spleens of mice. (B-C) An increased percentage of Foxp3⁺ Tregs in the CD4⁺ T-cell population was found in the livers of mice, shown in flow dot plot (B) and bar graph (C, P < .05). (D-E) An increased percentage of Foxp3⁺ Tregs in the CD4⁺ T-cell population was found in the spleens of mice, shown in flow dot plot (D) and bar graph (E, P < .05). (F) An increased number of tumor cells was correlated with an increased number of Treg cells in the livers and spleens of mice (P < .05). (G) An increased percentage of Tregs was found in the LNs (P < .05) and blood (P < .05) but not in the BM. Results from 1 of 3 representative experiments are shown. Error bars represent SD.