STAINING WITH HOECHST-33342 AND RHODAMINE-123 - AN ATTEMPT TO DETECT MULTIDRUG-RESISTANT PHENOTYPE CELLS IN LEUKEMIA

Development of resistance is the major cause of failure in chemotherap eutic treatments. We have previously shown that the level of labeling with Hoechst 33342 and rhodamine 123 in established cell lines was dec reased in cells with 'classic' MDR phenotype. This functional test was carried out using fluorescence image cytometry on living cells. We ap plied this protocol to patients with chronic lymphocytic leukemia. Alt hough a large variability of the labeling is observed in cells from he althy donors, this approach seems to be useful for early detection of P-gp-dependent resistance in leukemia cells and for identification of new reversing agents on patient lymphocytes.