Detection of minimal residual disease in pediatric B cell acute lymphoblastic leukemia by flow cytometry

Abstract

Objective: Improvements in the treatment of childhood acute lymphoblastic leukemia (ALL) provide a complete remission in many patients. Several study groups indicated that determining submicroscopic levels of leukemia cells in the bone marrow (minimal residual disease-MRD) on day 15 is affects the prognosis. Flow cytometry (FCM) is a fast and cheap approach when compared to other molecular methods. In this study, day 15 bone marrow MRD levels and demographic profile in B-ALL patients assessed in our laboratory between December 2010 and August 2011 were discussed. Material and Methods: Bone marrow samples obtained on treatment day 0 and 15 from patients diagnosed with ALL (n=45) and the expressions of CD10, CD11a, CD19, CD20, CD34, CD38, CD45 and CD58 have been determined using FACSCalibur according to the Associazione Italiana Ematologia Oncologia Pediatrica- Berlin Frankfurt Münster (AIEOP-BFM) protocol and evaluated by CELLQuest-Pro software. After determination of the number of nucleated cells with Syto16, the percentages of leukemic cells (blast-MRD percentage) detected in the nucleated CD19+ B cell population were classified as flow low (FLR), flow medium (FMR) and flow high (FHR) risk. Results: Six of the 45 cases (10 females, 35 males, 6.17±3.90 years) in our survey were MRD negative and 39 were positive. Eleven cases were determined as FLR (24.4%), 26 as FMR (57.8%) and 8 as FHR (17.8%) according to MRD risk. Conclusion: All of the evaluations were approved by an AIEOP-BFM partner (100%). Since 30 August 2011, our institute has become the first center in Turkey to evaluate its own cases with the qualifications of our AIEOP-BFM partner (Vienna). In the future, we plan to investigate correlation of MRD-FCM results with prognosis and relapse, and to compare these findings with the polymerase chain reaction results. © 2013 by Türkiye Klinikleri.