IN-VITRO STUDY OF THP-DOXORUBICIN RETENTION IN HUMAN LEUKEMIC-CELLS USING CONFOCAL LASER MICROSPECTROFLUOROMETRY

Microspectrofluorometry allows the analysis of fluorescent molecules s uch as anthracyclines in the nucleus of isolated living cells. Using t his technique, we confirmed that the amount of doxorubicin or THP-doxo rubicin incorporated into the nucleus was related to the resistant or sensitive character of K562 cells. it was then extended to the study o f fresh leukemic cells and kinetic studies were performed allowing the calculation of the retention rate (RR) of anthracycline (THP-doxorubi cin) into the cell nucleus. A reproducibility study confirmed the accu racy of the method. Blast cells collected in patients with acute myelo id (n = 22) or lymphoid (n = 8) leukemia, at diagnosis (n = 26), or in relapse (n = 4) have been studied. RR varied from 8 to 98% independen tly of the type of leukemia or the clinical status. RR did not correla te either with P-glycoprotein or with CD34 expression although this la tter result should be confirmed an a higher number of subjects. Among 18 patients presenting with AML at diagnosis, 14 have been treated wit h intensive chemotherapy including anthracyclines; the only one who ha d resistant disease had the lowest RR value. In conclusion, the result s obtained here show that microspectrofluorometry allows the performan ce of kinetic studies on fresh leukemic cells in order to quantify che moresistance phenomena related to drug transport.