Expression of Bmi-1 in CD34⁺ cells from MDS and MDS-AML. (A) Representative expression of Bmi-1 in bone marrow mononuclear cells from patients with RA, RAEB, and MDS-AML by flow cytometry is shown. The positivity of Bmi-1 in CD34⁺ cells was highest in the patient with case 44 with MDS-AML and also high in the patient with case 23 with RAEB. It was lowest in the patient with case 7 with RA. (B) The percentage of Bmi-1 expression in CD34⁺ cells according to MDS subtype is as follows: RA, 8.19% ± 8.20%; RARS, 16.62% ± 26.67%; RAEB, 55.27% ± 13.79%; RAEB-T, 70.45% ± 27.74%; MDS-AML, 88.68% ± 9.29%; and controls, 4.02% ± 3.89%. Data are expressed as percentage of mean ± SD of results obtained. ^*Progression to RAEB from RA or RARS. (C) Bmi-1 expression ratio in CD34⁺ cells was correlated with IPSS score in patients with MDS. The R value = 0.809 and P < .001 obtained indicates a good correlation between the 2 parameters (Bmi-1 [%] and IPSS score) considered. ^*Progression to RAEB from RA or RARS.