Detection of P glycoprotein activity on normal and leukemic CD34 cells

Rhodamine 123 is transported by the transmembrane efflux pump P glycoprotein (Pgp). We used this fluorescent dye to study multidrug resistance (MDR) activity in normal and leukemic CD34⁺ cells. These immature cells had a high degree of MDR activity. Among leukemic cells, CD34⁺ leukemias had significantly higher MDR activity as compared to CD34⁻ leukemias. Heterogeneous results in cell subpopulations, however, indicate that prognosis should be interpreted in the light of MDR analysis.