[Detection of multidrug resistance in patients with leukemia by using flow cytometry and RNA in situ hybridization]

Multidrug resistance (MDR) in leukemia and the reversal of MDR by cyclosporin A (CsA) in vitro have been studied through intracellular accumulation of daunorubicin (DNR) in leukemic myeloblasts. The study was carried out with real-time flow cytometry and relative expression levels of MDR, which is estimated by RNA in situ hybridization in 26 patients suffering from leukemia. The change of intracellular DNR accumulation in vitro after adding CsA was also analyzed. The results showed that intracellular DNR accumulation in newly diagnosed and treated patients (MDR1 negative) with remission increased significantly than that in refractory and relapsing patients (P < 0.01). Good reversal effect was obtained in refractory patients and MDR1 positive relapsing patients by adding CsA (P < 0.01). It is suggested that MDR detection by the two above-mentioned methods could help to project the chemotherapy schedule clinically, CsA had obvious reversal effect on the drug-resistant leukemic cells in vitro.